A new theory （ ） before it can be put into practice.(本题分数：2 分.)A new theory （ ） before it can be put into practice.(本题分数：2 分.) A、 must be tested B、 be tested C、 can be tested D、 to be tested
问题描述：
A new theory （ ） before it can be put into practice.(本题分数：2 分.)
A new theory （ ） before it can be put into practice.(本题分数：2 分.)
A、 must be tested
B、 be tested
C、 can be tested
D、 to be tested
答
A new theory （ A ） before it can be put into practice.(本题分数：2 分.)
A、 must be tested
B、 be tested
C、 can be tested
D、 to be tested