4.他若是想在下一届奥运会夺金的话，就要提高他的技术水平。（be to do）
1.He used to work at a local school.
2.A former classmate of mine wrote me a letter, telling me his thought of returning to the native land/motherland.
3.When (he was) asked why he was involved in the study, he kept silence (silent).
4.If he is to win the gold medal at the next Olympics, he needs to improve his technique.
5.She stared at the exit through which Mayor had disappeared and then looked around to see how others reacted to his absence.