问题
选择题
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
答案
答案：D
考查固定句型。It is+形容词+for sb. to do sth.句中it作形式主语。
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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
答案：D
考查固定句型。It is+形容词+for sb. to do sth.句中it作形式主语。