4. 解析：选A。细节理解题。从文章最后两句“But when we’re happy, our body works normally and we feel relaxed and positive. So we look bright, our skin glows, we feel healthy and it affects everyone around us”可知，应选A。

3. 解析：选B。细节理解题。根据文章第三段最后一句“ ...there’s the obvious tendency to smile when smiled at and there are less obvious changes that reflect emotions of surprise, anger or sadness such as a change in our heart rate and blood pressure”可知，答案应选B。

2. 解析：选D。词义猜测题。从后面的句子“...when we like the other person, we even copy his behaviour”可推知,“synchronise”相当于“respond accordingly”,意为“使同步；使同时发生”。

5. 解析：选C。remain是系动词，seated作表语。故选C项。

4. 解析：选D。give这一动作发生在谓语动词之前，故用v.-ing 的完成式，B、C两项用的是主动形式，故选D。

3. 解析：选B。A、C两项的句子主语与having got home不能构成主谓关系，应排除；lose是及物动词，表示“丢失的”，lose和book应是被动关系，故D项也不正确。

2. 解析：选C。句意为：木桥被流水冲走了。wash away冲走; wash down彻底冲洗;wash up(餐后)洗餐具；故选C。

5. The concert has been postponed to Saturday.

提升练习

4. My brother aims to be a scientist.

3. Since you have come here, you might as well make good use of the chance to improve your spoken English.