问题补充：
------What’s the matter with you?
------I have a .I have to see the dentist.
A. cold
B. sore throat
C. toothache
D. headache
答案：
A. cold
B. sore throat
(答案→)C. toothache
D. headache
解析：句意：--你怎么了？--我牙痛。我必须去看牙医。分析:cold感冒；sore throat咽喉痛；toothache牙痛; headache头痛。理解本题的下文：去看牙医，因此推断是牙痛。故选C
