I am very grateful to my high school teachers without help I wouldn’t be so excellent.A.

问题补充：

I am very grateful to my high school teachers, without help I wouldn’t be so excellent.

A. whom

B. their

C. which

D. whose

答案：

A. whom

B. their

C. which

(答案→)D. whose

解析：考查定语从句。句中先行词为my high school teachers，在句中作定语，故用关系代词whose。句意：我非常感激我的高中老师，没有他们的帮助我不会如此的杰出。故D正确。