632. drip n. 滴

Suddenly he heard the drip of the water.

突然他听见水滴声。

633. durable a. 耐用的，持久的

It convinced the public that fashionable clothes should be made durable. （2009年6月英语四级考试真题）

634. duration n. 持续，持续期间

In the unreal there is no duration and in the real there is no cessation虚幻的事物没有持久性，真实的事物不会停止存在；

635. dusk n. 黄昏，薄暮

The garden closes at dusk.

花园在黄昏时关闭。

636. leather n. 皮革

The factory processes leather.

这个厂加工皮革。

637. legislation n. 法律，法规；立法

The legislation affects legal as well as illegal immigrants.

立法不但影响非法移民也影响合法移民。

638. leisure n. 闲暇；悠闲

Yet, despite the competition, my 8-year-old daughter Rebecca wants to spend her leisure time writing short stories. （2007年12月大学英语四级考试真题）

639. loose a. 松的，宽松的

Though its structure is somewhat loose, the novel is not bad.

这部小说的结构虽然有些松散，但还是不错的。

640. loosen v. 解开，放松

I must take some exercise and loosen up my muscles .

我必须做些运动，以松弛我的肌肉。

641. earnest a. 认真的，诚挚的

He expressed earnest love to his motherland.

他抒发了对祖国的挚爱之情。

642. earthquake n. 地震

They’d lost their home and many or all of their possessions through fires, floods, earthquakes, or some other disaster. (2006年12月24日大学英语四级(CET-4)真题试卷(A卷))

643. echo n. 回音，回声

These two events are completely unrelated to, yet they echo each other in the message they send about the place of books and reading in American culture. (2006年12月24日大学英语四级(CET-4)真题试卷(A卷) 改错题)

644. elaborate a. 精心设计的，复杂的

Like animals, humans evolved with an elaborate mechanism for processing information about potential threats. （2006年12月24日大学英语四级(CET-4)真题试卷(A卷)）

645. elastic n. 橡皮圈（带） a. 有弹性的

Rigid casings will make the antenna more solid and rubber ones will allow it to stretch like an elastic band.

严格的封装使得这种天线更可靠以及更灵活。它可以象橡皮圈一样能被拉伸。

The rules are elastic.

规章是有弹性的。