单选题 That was so serious a matter that I had no choice but ______ the police.
A. to call in B. call in
C. calling in D. called in

【正确答案】 A
【答案解析】[解析] have/there is no choice but to do除……之外没有别的选择，这是个很有用的句式，考试频度很大。还可以将choice换为alternative，使用同样句式。