18. ⑴I'll help as much as I can, but there is a limit to what I can do.我会尽力帮忙，但我所能做的也是有限度的。 ⑵Her ambition knows no limit. 她的野心没有限度。 ⑶ We must limit our spending. 我们必须限制我们的开支。

⑷. I'm willing to help, within limits.我愿适当予以帮助。 ⑸I shall limit myself to three aspects of the subject. 我仅探讨这一问题的三个方面。

17.do research / carry out research

16.总结lie的用法：参考《三维设计》100页。

15.⑴ For the benefit of those people who arrived late, I’ll just go over the plan again.

⑵It is an expensive investment but it will benefit the company in the long run.

⑶A good diet is beneficial to health.

14.⑴He is a man of great strength.

　 ⑵The great strength of our plan lies in its simplicity.

13.⑴He’s burning with curiosity to know what was happening.

⑵It was curious that she didn’t tell anyone.

12.参考《三维设计》100页。

10. ①take up too much time and energy. ②use clean energy　 ③He is an energetic tennis player.11.⑴He lost his balance and fell over.

⑵You have to balance the advantages of living in a big city against the disadvantages. 你必须权衡住在大城市的利与弊。 ⑶All the parts of the building are in perfect balance.建筑物的各部分都显得非常匀称。

9. ①looked a bit tired； had been cleaning　 ②was tired of /was fed up with ③tired; have been working ④Teaching small children is very tiring.

8. have ;getting away with