It is said that the software on learning subjects for pupils in a very practical way.A. d

问题补充：

It is said that the software on learning subjects for pupils in a very practical way.

A. designed

B. designing

C. are designed

D. is designed

答案：

A. designed

B. designing

C. are designed

(答案→)D. is designed

解析：学习软件设计得很实用。本句主语是software, 是design的承受者。故D项正确。