12. ambiguous: adj.

①having more than one possible meaning 有不止一種意思的;有歧義

②uncertain in meaning or intention.意向不明的；曖昧的

ambiguously 　adv. 　ambiguousness 　n.

11. aluminium: chemical element; a light silvery metal. 鋁。

10. altitude. n.① height above sea-level 海拔，高度.eg :What is the altitude of the village?

② 常作復(fù)數(shù)，海拔甚高的地方。eg: It is difficult to breathe at these altitude.

在這些高的地方很難呼吸。

9. alternative. adj 作定語�？捎靡源�替其他事物的；另一可選用的；其他的。

　Have you got an alternative suggestion?你有沒有其他的建議？

8. algerbra. n .[u]. 代數(shù)學(xué)，代數(shù)。

7. alcoholic, adj ①酒精的；含酒精的；②由喝酒引起的。

6. advocate. v. speak publicly in favor of sth; recommend ; support. 擁護(hù)；提倡；主張。eg: Do you advocate banning cars in the city centers? 你支持禁止汽車在市中心通行這一主張嗎？ 　　advocacy. n .

5. adolescent adj 青春期的；青春期特有的。adolescence. n.

4. abundant. adj　　 ① more than enough ;plentiful.豐富的，充裕的

We have abundant proof of his guilt

② 作表語 ，富有某事物- in sth :having plenty of sth; rich insth。

3. absurd. adj ①unreasonable; not sensible. 不合理的；荒唐的；謊謬的

eg: What an absurd suggestion! 多么荒唐的建議

② foolish in a funny way. 愚蠢的；怪誕不經(jīng)的

eg: That uniform makes them look absurd. 他們穿著那種制服看起來怪模怪樣的。