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：考查冠词。第一空泛指一个三明治。第二空特指20:08分的火车。句意：当我们在等待20:08分的火车时，我吃了一个三明治。故C正确。