问题
选择题
I think ______ is necessary ______ us to do something to protect birds. [ ]
A. this, for
B. it, of
C. this, of
D. it, for
答案
答案:D
I think ______ is necessary ______ us to do something to protect birds. [ ]
A. this, for
B. it, of
C. this, of
D. it, for
答案:D