2. common / usual / ordinary 【解释】

common意为"普通的，平常的"，指常见的，常发生的，不足为奇的。

usual意为"通常的，习惯性的"，可用于一切频繁发生的事情。

ordinary意为"通常的，普通的，日常的，随时都可以碰到的"，与common意思接近。 【练习】用common，usual，ordinary填空。

1). He arrived later than _______.

2). Rabbits and foxes are _______ in Britain.

3). Tom Sawyer was a/an _______ American boy who kept getting into trouble.

4). Our _______ workday is eight hours.

5). He' s not an officer, but a/an ________ soldier.

Key: 1). usual 　　2). common 　　3). ordinary　 4). ordinary 5). common/ ordinary 3. convince / persuade 【解释】

convince "说服"，着重理智方面的"辩论，证明"。

persuade "说服"，着重情感上的"劝告"或"说服某人做/不做某事"。 【练习】用convince，persuade填空。

1). He _______ me that I should study law.

2). He _______ me not to stay.

3). The officials were eager to _______ us of the safety of the nuclear reactors.

4). I _______ (convince) I saw you there, but it must have been someone else.

5). How can we persuade him into _______ (join) us?

Key: 1). convinced　2). convinced/persuaded　3). convince 4). was convinced 5). joining III 词性变化 （旨在提供语法填空所需材料）

1. humour n. 幽默，诙谐 humorous adj.幽默的，诙谐的 2. fortune n.(大量) 财产，

大笔的钱；运气，命运 fortunate adj.幸运的，侥幸的 fortunately adv.幸运地，幸亏 3. bore vt. 使厌烦；n. 令人

讨厌的人(或事) bored adj.感到无趣的或单调的 boring adj.令人厌烦的，乏味的 4. mouth n. 嘴，口 mouthful n.一口；少量 5. direct adj.直接的；坦率

的adv.直接地vt.对准；指导 direction n.方向[pl.]说明书；指引；指导 director n.指导者，主管；董事；导演 6. explain v. 讲解，解释 explanation n.解释，说明，阐述 【练习】用括号内所提供词的适当形式填空。

1). ________ (fortune), the drowning child was saved.

2). He gave a ________ (humor) account of their trip to Spain first.

3). Tom went off in one ________ (direct) and Harry in another.

4). He now felt ready to take on the role of ________ (direct).

5). The earthquake left thousands of people ________ (home).

6). I' m stuffed. I couldn' t eat another ________ (mouth).

7). Not only are mothers not paid but also most of their ________ (bore) or difficult work is unnoticed.

8). There is no convincing ________ (explain) of the overall structure of the universe.

Keys: 1). Fortunately 2). humorous 3). direction 4). director

5). homeless 6). mouthful 7). boring 8). explanation