I       stop by sometime and thank her for all her help．

A．must        B．would         C．could         D．may

Robert made a call to his parents yesterday afternoon．To his disappointment,      of them answered it．

A．either            B．both         C．none          D．neither

When she called at his studio, she        that he had gone to Japan．

A．is told            B．was told         C．tells           D．told

—Did you get my letter?

—I received one just as I          ．

A．set out          B．had set out               C．was setting out        D．would set out

The researchers determine what type of plants the virus can infect（感染） and       insects can carry the virus．

A．those           B．why        C．which         D．how

At last, the boys found themselves in a pleasant park with trees providing shade and     down to eat their picnic lunch．

A．to sit        B．sat           C．sitting          D．having sat

He spent much of the evening with Robert Green,        he had hardly seen in the thirty years since they had worked together at CBS．

A．what            B．that          C．who          D．whom

Mr. Brown arranged for the taxi to come at six       she would not have to wait long at the station．

A．so that          B．even if           C．before          D．because

People aren’t watching      television as before on Christmas Day because they use their videos．

A．too much        B．too many          C．as much         D．as many

Children above 12 are able to take part in skiing or other activities        for them．

A．having designed            B．designing     C．to design         D．designed