1. Don’t get involved in love games too early. _______ (要是……该怎么办) you suffer from failure in love?
2. That car ___________________(尽给我添麻烦) ever since I bought it.
3. _______________________ (努力不吸入) the vapor, Thomas turned his head.
4. But for his wife’s encouragement, he _____________ (就不能发明那个机器).
5. It _________________________ (直到得到有关当局的批准) that we can start the job.
答案：
1. What if
2. has brought me nothing but troubles
3. Trying not to breathe in/ Trying to avoid breathing in
4. would have been unable to invent / could not have invented the machine
5. isn’t until we have the approval from the authority concerned