English is a language that many people around the world not speak perfectly but at least

问题补充：

English is a language that many people around the world not speak perfectly but at least understand.

A. might；could

B. will；must

C. would；might

D. can；may

答案：

(答案→)A. might；could

B. will；must

C. would；might

D. can；may

解析：情态动词might用于表推测时，和may相同，用于肯定句和否定句，所表示的可能性较小；could用于表推测时，语气与might差不多。