Some years ago the captain of a ship was very interested 　1 　medicine. He always 　2 　medical books to sea and liked to talk about different diseases. One day a lazy sailor on his ship pretended 　3 　ill. He lay on his bunk(铺位) and groaned(呻吟) as if he 　4 　very sick. The captain came to see him and was very pleased to have a patient to 　5 . He told the man to rest for a few days and 　6 　the other sailors do his work. Three days later 　7 　sailor pretended that he had 　8 　with his chest. 　9 　the captain looked in his medical books and told the “sick” man 　10 .

The other sailors were very 　11 　because they had 　12 　work to do. The patients had the best food and laughed at their friends when the captain was not 　13 . 　14 　the mate(大副) decided to punish the sick men and mixed up some soap, soot(烟灰), glue(胶水) and other unpleasant things. Then he got 　15 　from the captain to give his new medicine to the “sick” men. When they tasted the medicine, they really did feel ill. It was 　16 　horrible that one of the patients jumped out of his bunk, ran up on deck(甲板) and climbed the 　17 　mast(桅杆) on the ship. The captain 　18 　that the men had tried 　19 　him. So he made them 　20 　very hard for the rest of the ship on the sea.

20. The problem ______ very careful thought.

　 A．asks　　 B．calls for　　 C．demands for　　 D．need

19. My cousin is old enough ______ himself.

　 A．to were　　 B．to put on　　 C．to dress　　 D．to have on

18. ______ I know, he will be away for three weeks.

　 A．As soon as　　 B．As quickly as　　 C．As far　　 D．So far as

17. Production fell ______ 20% in May, ______ the same month of last year.

　 A．in, compared to　　　　　 　　　　B．by, compared to　　

　 C．with, compared with　　　　　　 D．by, comparing with

16. Climb as ______ as the top of the hill, and you may find the entrance ______ the cave.

　 A．high, in　　 B．far, into　　 C．long, to　　 D．far, to