—Why was Professor Zhang unhappy recently?—Because the theory he insisted on _________ wrong.
Our class _______ of thirty-two boys and twenty-three girls.
Now a lot of new technologies can ______ problems in industry.
When I returned home ,I found the window _____and something____.
Come and see me whenever ____ .
The invention of steam engine greatly sped up the industrial revolution, which _____ a lot to the take-off of the world.