1、【题目】heteachertoldthemsincelight________(travel)fasterthansound,lightning________(appear)togobeforethunder.

答案：

解析：

1、【题目】________(fail)severaltimes,theyneedsomeencouragement.

答案：

解析：

1、【题目】He asked me whether my brother ________ (fly) to Beijing.

答案：

had flown

解析：

暂无解析

1、【题目】I shall never forget ________ (meet) the late Premier Zhou during his inspection of our factory.

答案：

meeting

解析：

暂无解析

1、【题目】He fell asleep immediately last night; he must ________ (be) very tired.

答案：

have been

解析：

暂无解析

1、【题目】Agreatnumberofsmallpowerstations________(setup)intheircounty sinceliberation.

答案：

解析：

1、【题目】Those who’d like to visit the exhibition ________ (sign) your names here.

答案：

sign

解析：

暂无解析

1、【题目】Some molecules are large enough ________ (see) under the electronic microscope.

答案：

to be seen

解析：

暂无解析

1、【题目】A great number of small power stations ________ (set up) in their county since liberation.

答案：

have been set up

解析：

暂无解析

1、【题目】A beam of light will not bend round corners unless ________ (make) to do so with the help of a reflecting device

答案：

made

解析：

暂无解析

1、【题目】Somemoleculesarelargeenough________(see)undertheelectronicmicroscope.

答案：

解析：