I ate sandwich while I was waiting for 20:08 train. A. the aB. the theC. a theD. a a

问题补充：

I ate sandwich while I was waiting for 20:08 train.

A. the, a

B. the, the

C. a, the

D. a, a

答案：

A. the, a

B. the, the

(答案→)C. a, the

D. a, a

解析：我吃了一个三明治，一般所指；特指哪一列火车，用定冠词the.