The boy student is poor in health now; his parents wish that his health when he grows upA.

问题补充：

The boy student is poor in health now; his parents wish that his health when he grows up

A. can improve

B. could improve

C. can be improved

D. could be improving

答案：

A. can improve

(答案→)B. could improve

C. can be improved

D. could be improving

解析：考查虚拟语气。句意：这个男学生现在健康状况不佳；他的父母希望他的健康在他长大后能有所提高。wish后宾语从句的虚拟语气只有两种时态，一是一般过去时，一是过去完成时。即若表示对现在或将来的虚拟就用一般过去时；若表示对过去的虚拟就用

过去完成时。从句的时态完全不以wish 的形式而变化。结合语境可知从句表示的是就将来的虚拟，故用过去时态。Improve一般不用于进行时态，与语境不符，故选B。