Question

If you are in any doubt as to _____ you should be doing these exercises, consult your doctor.

A．that

B．which

C．what

D．whether

Answer 1

D

试题分析：考查宾语从句。Whether引导宾语从句whether you should be doing these exercises;句意：对于你是否应该做这些实验，如果你有任何疑问，请咨询你的医生。故D正确。
点评：对宾语从句的考查主要集中在语序和考查和连接词的词义辨析上。