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来源：杭州中考网&&&&&&&& 17:03:43
　　Since 和 for 的用法
　　表示过去已经开始持续到现在的动作或状态常用的时间状语有：for, since, how long, so far, these days等。
　　Since+过去点的时间，for+一段时间(数词+量词)，此划线部分用how long提问。
　　一、since短语或从句表示过去的动作延续至今，since之后的时间为一点。 如：
　　Mr. Smith has worked here since 年以来，史密斯先生一直在这工作。
　　He&s learned about 5,000 English words since he went to college. 他上大学以来大约学了五千个英语单词。
　　二、for短语表示动作延续多长时间，for的宾语为时间段。 如：
　　We have known each other for twenty years. 我们认识有二十年了。
　　I haven&t seen her for a long time. 我好久没有见到她了。
　　练习：用since和for填空
　　1) ______ two years 2) _______ two years ago 3) _______ last month
　　4) ______ 1999 5) _______ yesterday 6) _______ 4 o&clock
　　7) ______ 4 hours 8) _______ an hour ago 9) _______ we were children
　　10) _____ lunch time 11) ______ she left here
　　1. He has lived in Nanjing ________ the year before last.
　　2. I&ve known him __________ we were children.
　　3. Our teacher has studied Japanese _________ three years.
　　4. She has been away from the city ___________ about ten years.
　　5. It&s about ten years __________ she left the city.
　　2.短暂性转换延续性
　　①arrive at/in sw. get to/reach sw. come/go/move to sw.
　　& be in sw./at school/at home/on the farm/be here/be there
　　1) He got to Beijing five minutes ago.
　　He ________ _________ _________ Beijing for _________ _________.
　　2) I moved to the USA last year.
　　I ________ ________ __________ the USA since __________ __________.
　　3) I went home yesterday.
　　I _______ ________ _________ home for _________ __________.
　　4) They came here last week.
　　They _________ _________ here since _________ __________.
　　②come/go back, return & be back come/go out & be out
　　1) He came out two years ago.
　　He _________ __________ _________ for __________ __________.
　　2) We return to Fuzhou yesterday.
　　We ________ ________ _________ to Fuzhou since __________.
　　③become & be
　　1) I became a teacher in 2000.
　　I ________ __________ a teacher for _________ _________.
　　2) The river became dirty last year.
　　The river _________ _________ dirty for _________ __________.
　　④close & be closed open & be open
　　1) The shop closed two hours ago.
　　The shop ________ _________ _________ for _________ _________.
　　2) The door opened at six in the morning.
　　The door ________ ________ ________ for six hours.
　　⑤get up & be up die & be dead
　　leave sw. & be away from sw.
　　fall asleep/get tot sleep & be asleep
　　finish/end & be over marry & be married
　　1) I got up two hours ago.
　　I ________ ________ ________ since ________ ________.
　　2) He left Fuzhou just now.
　　He _______ ________ ________ _________ Fuzhou for five minutes.
　　3) My grandpa died in 2002.
　　My grandpa _______ _______ ________for _______ ________.
　　4) The meeting finished at six.
　　The meeting ________ ______ ______ for six hours.
　　5) I got to sleep two hours ago.
　　I ________ _________ _________ since _________ __________.
　　6) They married in 1990.
　　They ________ _________ __________since _________.
　　⑥start/begin to do sth. & do sth. begin & be on
　　1) I began to teach at this school in 1995.
　　I ____ ____ at this school since ____.
　　2) The film began two minutes ago.
　　The film ____ ____ ____ for ____ ____.
　　⑦borrow & keep lose & not have buy & have put on & wear
　　catch/get a cold & have a cold get to know & know
　　1) They borrowed it last week.
　　They _________ _________ it since __________ __________.
　　2) I bought a pen two hours ago.
　　I _________ _________ a pen for ________ __________.
　　3) I got to know him last year.
　　I _________ __________ him since __________ __________.
　　4) I put on my glasses three years ago.
　　I __________ __________ my glasses for _________ _________.
　　⑧have/has gone to & have been in
　　1) He has gone to Beijing.
　　He ____ ____ _____ Beijing for two days.
　　⑨join the league/the Party/the army
　　& be a league/a Party member/a soldier
　　& be a member of the league/the Party
　　& be in the league/the Party/the army
　　1) He joined the league in 2002.
　　He ________ _________ a _________ _________ for two years.
　　He ________ __________ a __________ ___________ the __________ for two years.
　　He ____________ ___________ ___________ the league for two years.
　　2) My brother joined the army two years ago.
　　My brother __________ __________ a ___________ for ___________ ___________.
　　My brother ___________ ___________ in ____________ ___________ for two years.
　　3.汉译英
　　1)这本字典我已买了三年了。
　　2)他离开中国三年了。
　　3)我认识他们五年了。
　　4)他们已去了美国五年了。
　　5)自从他搬到福州，他就住这儿了。
　　6)他们已经结婚10年。
　　7)我妹妹成为一个大学生已经三年。
　　8)这会已开了多长时间了?
　　9)这门已经关了两天了。
　　10)我入团2年了。
　　I __________ ___________ ___________ two years ago.
　　I __________ ___________ a ___________ ___________ for two years.
　　I __________ ___________ a ___________ of __________ _________ for two years.
　　I __________ ___________ ____________ the __________ for two years.
　　11)自从1999年以来他们就认识。
　　12)我来到农场已5年了。
　　4.划线提问
　　1) I have been there for two days.
　　__________ _________ __________ you __________ __________ ?
　　2) My father has lived here since 2000.
　　_________ _________ __________ your father _________ __________?
　　3) He left here yesterday.
　　_________ ________ he _________ __________?
　　4) They bought a book two hours ago.
　　__________ ___________ they __________ a book
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你可能喜欢详解Python中for循环的使用方法
投稿：goldensun
字体：[ ] 类型：转载 时间：
这篇文章主要介绍了Python中for循环的使用方法,是Python入门中的基础知识,需要的朋友可以参考下
&for循环在Python中有遍历所有序列的项目，如列表或一个字符串。
for循环语法如下：
for iterating_var in sequence:
statements(s)
如果一个序列包含一个表达式列表，计算第一个。然后，在序列中的第一项被分配给迭代变量iterating_var。接着，语句块被执行。列表中的每个项目分配给iterating_var，并且statement块被执行，直到整个序列完成(到尾部)。
#!/usr/bin/python
for letter in 'Python':
# First Example
print 'Current Letter :', letter
fruits = ['banana', 'apple', 'mango']
for fruit in fruits:
# Second Example
print 'Current fruit :', fruit
print "Good bye!"
当执行上面的代码，产生以下结果：
Current Letter : P
Current Letter : y
Current Letter : t
Current Letter : h
Current Letter : o
Current Letter : n
Current fruit : banana
Current fruit : apple
Current fruit : mango
通过遍历序列索引：
通过每个项目进行迭代的一种替代方法是：通过索引偏移量序列本身。下面是一个简单的例子：
#!/usr/bin/python
fruits = ['banana', 'apple', 'mango']
for index in range(len(fruits)):
print 'Current fruit :', fruits[index]
print "Good bye!"
当执行上面的代码，产生以下结果：
Current fruit : banana
Current fruit : apple
Current fruit : mango
在这里，我们采用内置函数len()，它计算元组元素的总数量以及range()内置函数给我们的实际遍历顺序。
循环使用else语句
Python支持与循环语句相关联的else语句。
&&& 如果else语句与for循环使用，执行else语句时，循环已经迭代完成列表。
&&& 如果在else语句使用while循环，当条件为假时，else语句被执行。
下面的例子演示了一个else语句，语句搜索素数从10到20的组合。
#!/usr/bin/python
for num in range(10,20): #to iterate between 10 to 20
for i in range(2,num): #to iterate on the factors of the number
if num%i == 0:
#to determine the first factor
#to calculate the second factor
print '%d equals %d * %d' % (num,i,j)
break #to move to the next number, the #first FOR
# else part of the loop
print num, 'is a prime number'
当执行上面的代码，产生以下结果：
10 equals 2 * 5
11 is a prime number
12 equals 2 * 6
13 is a prime number
14 equals 2 * 7
15 equals 3 * 5
16 equals 2 * 8
17 is a prime number
18 equals 2 * 9
19 is a prime number
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