He made clear when he would give us a lecture on global warming.
A. this
B. it
C. that
D. these
网友回答
A. this
(答案→)B. it
C. that
D. these
解析：考查宾语从句。本题中it是形式宾语，真正的宾语从句是when he would give us a lecture on global warming.句意：他说的很清楚，他何时要给我们做一个关于全球变暖的演讲。故B正确。