问题补充:
It was she that a sharp whistle, which makes possible for us to catch the thief.
A. gave off; this
B. gave out; that
C. gave; it
D. sent out; them
答案:
@@A. gave off; this@@B. gave out; that@@(答案)C. gave; it@@D. sent out; them
解析:前半句即主句是强调句,强调she;后半句是which引导的非限制生定语从句,it为形式宾语,指代真正的宾语即动词不定式短语to catch the thief.