Don’t be afraid of asking your teachers for help it is needed.A. asB. sinceC. unlessD. whe

问题补充：

Don’t be afraid of asking your teachers for help it is needed.

A. as

B. since

C. unless

D. when

答案：

A. as

B. since

C. unless

D. when

解析：D

解析考查连词。句意为：如有需要，不要害怕向老师求助。此处when相当于if，表示条件，其他不符合语意。