数据流程图是分层次的，绘制时采取（）逐层分解的办法.

A.从下到上

B.从左到右

C.从前到后

D.自顶向下

Clinical evidence began to ________， suggesting that the new drugs had a wider range of useful

activities than had been predicted from experiments in animals.[ ]

A. operate  

B. strengthen

C. approve  

D. accumulate