用所给动词的适当形式填空：

Look!One of them ________(swim)in the lake．

用所给动词的适当形式填空：

Thank you for ________(help)me carry the basket．

用所给动词的正确形式填空：

Masha ________(cook)when the doorbell ________(ring)．

用所给动词的正确形式填空：

I ________(read)a history book when someone ________(knock)at the door．

用所给动词的正确形式填空：

Mr Wang spends a lot of time writing his novel(小说)every day．He ________ still ________(work)at midnight last night．

用所给动词的正确形式填空：

The street seller ________(sell)clothes when he ________(find)a purse on the ground．

用所给动词的正确形式填空：

Doctor Liu was on duty last night．He ________ still ________(work)in the hospital at 10 p.m．

用所给动词的正确形式填空：

Some students from Class Four ________(play)basketball when I ________(see)them on the playground．

用所给动词的正确形式填空：

The driver ________(drive)home when it ________(rain)last night．

用所给动词的正确形式填空：

The students ________(have)a biology class when the visitors ________(come)．