下列化合物均为天然萜类化合物

对这些萜类化合物叙述错误的是[ ]

A．a和c互为同分异构体

B．a和b互为同系物

C．a、b能与溴水反应

D．一定条件下b能转化为a

—Can you understand ________ the teacher said?

—No, I can't catch anything. He spoke too fast. [ ]

A. what

B. if

C. that

D. how