Ⅰ.单句语法填空
1．It was not until the 19th century that heat ________ (be) considered a form of energy.
2．Not until he returned ________ we have supper.
3．It was he ________ came running into the classroom with the news.
4．We were told that it was in that room ________ the Republicans held the important meeting.
5．It is Peter and Mary ________ often help us with our lessons.
6．It was two years ago ________ Mr Green went to America.
7．No sooner had he arrived ________ they felt irritated.
8．So absurd ________ his manner that everyone stared at him.
9．It ________ Mike and Mary who helped the old man several years ago.
10．Seldom ________ he visit his parents because he is far away from them.
