Such a good opportunity once might never come again.A. lostB. to loseC. losingD. loses

问题补充：

Such a good opportunity, once , might never come again.

A. lost

B. to lose

C. losing

D. loses

答案：

(答案→)A. lost

B. to lose

C. losing

D. loses

解析：考查状语从句的省略：句意：这样的好机会，一旦错过了，可能再也不能回来了。这句话的状语从句完整的是：Once a good opportunity is lost，当主从句的主语一致的时候，可以省略从句的主语和be动词，所以选A。