1.Excuse me.____you____my dictionary?I can't find it.选DA.Do,see B.Did,see C.Are,seeing D.Have,seen2.Lily was dancing,while Jim___the piano.选BA.played B.Was playing C.were playing D.plays3.These inventions are very important and __the world.选C A

1.Excuse me.____you____my dictionary?I can't find it.选DA.Do,see B.Did,see C.Are,seeing D.Have,seen2.Lily was dancing,while Jim___the piano.选BA.played B.Was playing C.were playing D.plays3.These inventions are very important and __the world.选C A
1.Excuse me.____you____my dictionary?I can't find it.选D
A.Do,see B.Did,see C.Are,seeing D.Have,seen
2.Lily was dancing,while Jim___the piano.选B
A.played B.Was playing C.were playing D.plays
3.These inventions are very important and __the world.选C A.is going to change B.has changed C.have changed D.has changing
4.Have they written to each other___?选A
A.recently B.already C.last month D.two weeks ago
5.The famous scientists ____Beijing two days ago.选C A.arriced B.have got to C.left D.have been away from
6."How long have you known Jack?" "---"选B .A.Tow year ago B.Since 1999 C.For two years ago D.In 1999
7.We had planted (plant)many trees during the last 3 years.为什么用had planted
8.Spring in China lasts(last)from February to April.为什么用lasts
9.When did you came here(come)?为什么用did …came?I came(come)when I was five years old .为什么用came?
10.By the time they got there ,the bus had left(leave)already.为什么用had left?
11.She has just gone(go)out.为什么用has…gone?

1.Excuse me.____you____my dictionary?I can't find it.选DA.Do,see B.Did,see C.Are,seeing D.Have,seen2.Lily was dancing,while Jim___the piano.选BA.played B.Was playing C.were playing D.plays3.These inventions are very important and __the world.选C A
1完成时态跟过去时态除了写法不一样外,完成时还表示对现在造成了一定的影响,强调造成了影响.所以选D
2是while连接前后两句,根据前句用了过去进行时,后句也应该用同样的时态.so选 B
3强调对现在是很重要的,同1,应该用完成时,而且inventions是复数,so选 C
4中AB是完成时的标志用语,CD只用过去式,而already是用于肯定句的,疑问句应该用yet
5中two days ago表明该句是过去时,所以排除了BD,A改成arrived at才正确.所以选C
6是完成时,可以排除了AD,C用法有误,应改成For two years ,B表示从1999 年（认识到现在）符合语境
7during the last 3 years是过去完全时的标志用语
8主语是Spring,是单数,in China 可置于句末,意思一样.所以加s.另外last一般不用进行时
9第一个空我认为是答案错了,应该用come.第二个像这种 when+句子的从句中,主句严格来说应该用had come（比从句再前一个时态）,但如果要求不严的话用过去式也可以.
10By the time 是完成时的标志用语,再根据其从句用了过去时,主句应该用比从句前一个时态的语态,过去完成时
11这应该有上下文的吧..根据上下文应该她的走对现在有一定的影响.所以用完成时.
希望能帮到您.

1.：have been 现在完成时，在说这句话之前所发生的：你看到我的字典了吗？我找不到了！
2：前一句Lily was dancing应该是过去进行时，后面连接词是while，所以连接两个相同时态的句子， Jim Was playing the piano，意思是：Lily 在跳舞，而Jim在弹钢琴！
3：选择现在完成时，体现了对现在产生的影响！这些发明很重要，已经改变了世界...

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1.：have been 现在完成时，在说这句话之前所发生的：你看到我的字典了吗？我找不到了！
2：前一句Lily was dancing应该是过去进行时，后面连接词是while，所以连接两个相同时态的句子， Jim Was playing the piano，意思是：Lily 在跳舞，而Jim在弹钢琴！
3：选择现在完成时，体现了对现在产生的影响！这些发明很重要，已经改变了世界
4：他们最近在通信吗？B。already符合题意CD一般过去时的时间表示
5：A：应该为arriced in 再看看后面的时间是two days ago 为一般过去时，所以选择left
6：问题是：你认识jack多久了？ 只有B选项最符合语态 A明显不对，B自从1999年以来 C，语句就不对，D在1999年
8：主语为Spring春天，陈述的是一个事实，中国春天从二月份持续到四月份，故用lasts
10:当他们到那的时候，汽车已经走了！他们到那的语态是一般过去时了，所以车在他们到之前走的，应该是过去完成时
只是个人的想法，希望能帮到你！

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