按要求改写句子。

CNN has been on the air for more than twenty years．(对画线部分提问)

________　________ has CNN been on the air?

按要求改写句子。

Many factors have had an effect on American pronunciation．(改为同义句)

Many factors have ________ American pronunciation．

用动词的正确形式填空。

Visitors ________(request)not to touch the exhibits．

用动词的正确形式填空。

I’ll return the magazine to the library as soon as I ________(finish)it．

用动词的正确形式填空。

He is reading the book he ________(buy)recently．

用动词的正确形式填空。

The boy ________ always ________(talk)in class．

用动词的正确形式填空。

When he ________(arrive), we’ll go to meet him．

用动词的正确形式填空。

Practice ________(make)perfect．

选择下列所给单词对应的图片。

1．structure ________

2．reference ________

3．flick ________

4．combination ________

5．attempt ________

6．variation ________

7．linguistics ________

8．settler ________

写出描述下面物体或情景的词。