I think ______ is necessary ______ us to
题型:选择题
问题:
I think ______ is necessary ______ us to do something useful to protect the birds.
A.this; for
B.it; of
C.this; of
D.it;for
I think ______ is necessary ______ us to do something useful to protect the birds.
A.this; for
B.it; of
C.this; of
D.it;for