V. 选择填空：从A、B、C中，选出一个最佳答案完成句子。
17. --Mom, something is wrong with my teeth. I can’t eat anything.
--What about going to the ________at once?
A. director B. dentist C. designer
18. I like the waiter because he was really _______ when I ordered food.
A. nervous B. patient C. strong
19. --I saw you come to school by taxi this morning.
--Oh, I _______come to school by bike, but it’s raining today.
A. never B. hardly C. usually
