Do you know how to ( ) a map?A.look B.watch C.read
read a map
意思是"读地图; 看地图"
watch 后面一般接 TV,
不能接 map
泛指看一个东西, 只是瞬间的动作, 并不表示看懂.
翻译; 你知道如何读地图吗?
希望对你有帮助!
为您推荐：
其他类似问题
b和c的话，个人语感选C
选C watch更适用于看时间之类的
look是泛泛的看
你好，选择Cread a map是看地图的意思~祝：学习进步，更上一层楼！ (*^__^*)不明白的再问哟，请及时采纳，多谢！~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
选C，read,read a map,阅读地图，强调看地图的内容；look at a map,看地图，强调看地图的过程，根据题意，强调看地图的内容。
本题选CDo you know how to read a map？你会看地图吗？A选项look表示单纯的“看”，可以是看任何东西，仅仅是指把目光放在某个东西上please look at the blackboard.请看到黑板上B选项watch表示“观看”，是“看电视”“看电影”的“看”I always go to watc...
c,可以看成看书read book
read a map
意思是"读地图; 看地图watch 后面一般接 TV,
不能接 maplook
泛指看一个东西, 只是瞬间的动作, 并不表示看懂....翻译; 你知道如何读地图吗?
扫描下载二维码Choose the right map. A wide variety of maps are available for a wide variety of uses.
For example, there are road maps for drivers with highways and byways.
Tourist maps for sightseeing, with famous landmarks or conspicuous celebrities.
Topographic maps for hikers maps maps for hikers or back country, featuring paths and campgrounds.
Sectionals, or maps for pilots that feature air routes, terminal areas, plus landmarks and tall things that planes would be wise to avoid.
A good general free online map for certain parts of the world is Google Maps. However, this may not be available to you when needed, so it's important to learn how to read printed maps too.
Check the map's orientation. Most maps are drawn with north located at the top.
Sometimes this may be depicted using a compass rose. Or, it might simply be stated to be the assumption of the map. If there is no indication to the contrary, presume it is north at the top.
Understand the scale of the map. The map scale shows you a ratio of map distance to real distance. These differ in size from map to map. Look for the scale, generally located on the side or bottom of the map. It will look something like 1:100,000, which denotes that 1 unit on the map is the equivalent of 100,000 units in real life. In general, the following scales work best as stated:
Get a 1:25,000 map for walking
Get a 1:190,000 map for driving
Get a 1:24,000,000 map for seeing the whole world.
To determine how far your destination is, use a ruler and the scale to measure how many miles it is from point A to B.
For example, if your map's scale is 1:250,000, and the distance from point A to point B is 6 inches (15.2 cm), the total distance is 6 * 250,000 = 1,500,000 inches (3,810,000 cm). One mile is 63,360 inches, so the distance from point A to point B is 1,500,000 ÷ 63,360 = 23.7 miles (1 kilometer is 100,000 cm, so the distance from point A to point B is 3,810,000 ÷ 100,000, or 38.1 km).
Note the latitude and longitude. If you're traveling to the next town, this isn't so important. But if you are sailing, flying, or touring long distances, this might be useful.
The latitude refers to the distance in degrees north or south of the equator.
The longitude refers to the distance in degrees east or west of the Greenwich Meridian Line.
Each degree is divided into 60 minutes, with each minute representing a nautical mile (or 1.15 land miles/1.85km). This means that one degree is the equivalent of 60 nautical miles or 69 land miles/111km.
The latitude is represented by the numbers on the side of the map.
The longitude is represented by the numbers at the top and bottom of the map.
Where the latitude and longitude cross at your location is your point of reference.
Latitude and longitude points are often used when there are no landmarks or roads to help determine a location.
Tip: If you have trouble remembering which is which, the longitude lines are "long." The diameter of the longitudinal lines is roughly constant, whereas the latitude lines get progressively smaller, the further they are from the equator.
Learn to read contour lines. How high or flat the land is is represented on the map with contour lines. Each line represents a standard height above sea level.
When contour lines are close together, this means that the gradient is steep (the closer together, the steeper the gradient becomes).
When the contour lines are further apart, the gradient is flatter, so the further apart they are located, the flatter the ground on the map.
Examine the legend. Most maps have a legend or key of symbols on the map itself. Get familiar with how your map represents data—that is key to understanding the rest of the map. In general, maps do the following:
Lines in varying sizes, colors, and unbroken or broken lines depict roads, from lanes to freeways and all in between.
Mountains tend to be shown as brown or green, and are height-dependent: darker at the bottom, lighter or white at the top.
Rivers, lakes, the ocean and other water bodies are generally shown in blue.
Forests, woods, parks, golf courses, or other large bodies of trees or green space are usually depicted in green.
Towns and city limits are often shown in a pastel pink or yellow, and the size and boldness of their names indicate relative population size or importance.
Buildings tend to be shown in gray or black colors.
Figure out where you are. You have your map and you're ready to use it. Now you need to figure out where you are before you can plot where you're going.
You can do so by matching what you can see in real life with what is on the map. Common features that help identify your location on a map includes road names, landmarks and prominent natural features, like rivers.
If you have a compass, align the map with the direction shown on the compass. Or, use the sun or markers to help you do this.
A good way to find your location if you are unsure is to find two landmarks. For example, if you can see a prominent tower in front of you, and a city at 45 degrees to your left. Find those two landmarks on the map. Align the map so that the point in front of you is at the top of your map, and draw a straight line from that point down. Then draw a line from the diagonal landmark, till it intersects the first landmark. The point that they intersect is roughly your location. Look for closer landmarks to zero in on your position.
Find your destination. Now it's time to figure out where you want to go.
If you just want to go from one place to another, all you need to do is to plot that single route out.
If there are several places you intend to go to, you may want to plan your route in such a way that you visit all the places in the shortest possible manner. You can do so by going to the nearest places first after which you will go to the further places.
Use the map's index. Some maps, such as a Thomas Guide, have indexes stating the location of certain places on a map. This location could be grid numbers or pages.
Take note of a map's scale so that you can estimate your travel time, and if you are taking longer then you expected, you can stop to recheck your map.
Don't forget to check the map's legend so will know what you are looking at.
Plot the route out. Now that you have figured out where you want to go, plot the route for your first leg of your journey.
Use can also use a pencil, if you don't want to permanently mark up your map.
Travel to the desired spot with the map. Keep tabs of checkpoints along the way—if you miss a turn, you could be seriously off course before you realise it.
Can I get clarification about the scaling of the map?
wikiHow Contributor
A scale is the ratio between the distance on the map and the real distance on the ground.
How do I find the hundredth block on a map?
What is the difference between red dot line and green dot line?
How to find route from point a to point b?
How do I do the striping method of calculating on a map?
How do you find the direction of the place?
200 characters left
A series of similar features makes navigation difficult. For example, it would be difficult navigating around New York City based on building names or in a marshland by water bodies. Try to make mental notes of what is not that common in the area to help guide you along your route.
Try to stay on marked roads or trails. While cutting across apparent green spaces may be the shortest route possible, they may be filled with obstacles ranging from fencing and walls to soggy ground or dense vegetation.
Magnifying glass (optional)
Glasses or contact lenses (optional)
Protractor or compass (optional)
Small cord (optional)
Thanks to all authors for creating a page that has been read 455,823 times.
Click a star to vote
Click a star to vote
Co-authors:
Views:&455,823
74% of people told us that this article helped them.dictionary - How to check if a map contains a key in go? - Stack Overflow
to customize your list.
Join the Stack Overflow Community
Stack Overflow is a community of 6.5 million programmers, just like you, helping each other.
J it only takes a minute:
I know I can iterate over a map m by,
for k, v := range m { ... }
and look for a key but is there a more efficient way of testing a key's existence in a map? Thanks. I couldn't find an answer in the .
2,42842158
3,32141932
One line answer:
if val, ok := dict["foo"]; ok {
//do something here
Explanation:
if statements in Go can include both a condition and an initialization statement. The example above uses both:
initializes two variables - val will receive either the value of "foo" from the map or a "zero value" (in this case the empty string) and ok will receive a bool that will be set to true if "foo" was actually present in the map
evaluates ok, which will be true if "foo" was in the map
If "foo" is indeed present in the map, the body of the if statement will be executed and val will be local to that scope.
12.2k2690191
11.1k72538
Edit: The following answer is prior to Go 1. Starting with Go 1, it is no longer accurate / valid.
In addition to , you should read . In the section on , they say, amongst other things:
"An attempt to fetch a map value with a key that is not present in the map will cause the program to crash, but there is a way to do so safely using a multiple assignment."
var seconds int
var ok bool
seconds, ok = timeZone[tz]
"To test for presence in the map without worrying about the actual value, you can use the blank identifier, a simple underscore (_). The blank identifier can be assigned or declared with any value of any type, with the value discarded harmlessly. For testing presence in a map, use the blank identifier in place of the usual variable for the value."
_, present := timeZone[tz]
73.7k11109145
53k6103120
Searched on the
and found a solution posted by Peter Froehlich on 11/15/2009.
package main
import "fmt"
func main() {
dict := map[string]int {"foo" : 1, "bar" : 2}
value, ok := dict["baz"]
fmt.Println("value: ", value)
fmt.Println("key not found")
Or, more compactly,
if value, ok := dict["baz"]; ok {
fmt.Println("value: ", value)
fmt.Println("key not found")
Note, using this form of the if statement, the value and ok variables are only visible inside the if conditions.
3,32141932
Short Answer
_, exists := timeZone[tz]
// Just checks for key existence
val, exists := timeZone[tz]
// Checks for key existence and retrieves the value
Here's an .
Longer Answer
section of :
An attempt to fetch a map value with a key that is not present in the map will return the zero value for the type of the entries in the map. For instance, if the map contains integers, looking up a non-existent key will return 0.
Sometimes you need to distinguish a missing entry from a zero value. Is there an entry for "UTC" or is that the empty string because it's not in the map at all? You can discriminate with a form of multiple assignment.
var seconds int
var ok bool
seconds, ok = timeZone[tz]
For obvious reasons this is called the “comma ok” idiom. In this example, if tz is present, seconds will be set appropriately if not, seconds will be set to zero and ok will be false. Here's a function that puts it together with a nice error report:
func offset(tz string) int {
if seconds, ok := timeZone[tz]; ok {
return seconds
log.Println("unknown time zone:", tz)
To test for presence in the map without worrying about the actual value, you can use the blank identifier (_) in place of the usual variable for the value.
_, present := timeZone[tz]
171k2589132
var empty struct{}
var ok bool
var m map[string]struct{}
m = make(map[string]struct{})
m["somestring"] = empty
_, ok = m["somestring"]
fmt.Println("somestring exists?", ok)
_, ok = m["not"]
fmt.Println("not exists?", ok)
Then, go run maps.go
somestring exists? true
not exists? false
if len(m) == 0 {
13.3k122956
Your Answer
Sign up or
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Post as a guest
By posting your answer, you agree to the
Not the answer you're looking for?
Browse other questions tagged
rev .24557
Stack Overflow works best with JavaScript enabledPeters Projection World Map | Live Learn Evolve
I am the co-founder of Live Learn Evolve, creating this platform to facilitate a wiser, more enlightened and compassionate world. Always keen to connect with the like-minded and talk about how novel it is to be alive on this organic rock floating in infinite space.
Connect on
Pingback: ()
Pingback: ()
Pingback: ()
Pingback: ()
Pingback: ()
Pingback: ()
Pingback: ()
Pingback: ()
No more articles