We entered the café and sat down by the window waiting .A. to serveB. to be servedC. serv

问题补充：

We entered the café and sat down by the window, waiting .

A. to serve

B. to be served

C. serving

D. served

答案：

A. to serve

(答案→)B. to be served

C. serving

D. served

解析：答案：B考查非谓语动词。根据句意，句子主语We与非谓语动词serve之间存在被动关系，且serve的动作尚未发生，故使用不定式的被动形式。