21. --John has got a very good job in the government.
-- he looks so happy.
A. It’s natural B. That’s because C. No wonder D. As though
22. There is no doubt the boxes were then put on a train for Konigsberg, was at that time a German city on the Baltic Sea.
A. whether, which B. that, where C. that, that D. that, which
23. Though young, he succeeded in taking the machine skillfully and then put it together without any difficulty.
A. out B. down C. apart D. up
24. Last summer I took a course on poisonous gases.
A. how to deal with B. what to deal with
C. how to be dealt with D. what to be dealt with