人一天的主食主要是米饭或面食，这是因为人体生命活动的主要能源物质是（　　）

人的生活离不开营养物质和氧气，同时还需要排出体内产生的代谢废物．人体是一个统一的整体，各个系统之间存在着密切的联系．图是人体进行消化吸收、呼吸、循环、排泄等生理活动的部分结构示意图，表格为取自图四中不同结构液体的成分含量（单位：s/100m1），请据图回答下列问题（中填标号，横线上填文字）：

A.popular              B.when             C.at all

D.interests            E.pick up               F.in all

    Do you know what gifts Western kids enjoy best? How do they give them? Let's have a quick look.The most ____gifts are fashionable things like the new video games, CDs and DVDs. A video game costs about US$60 and CDs or DVDs are cheaper at around US$20.Girls like to give jewellery (宝石) they make themselves. They ____pretty beads (串珠) in DIY shops and put them together in their own way.

    US kids give gifts according to their friends' ____. Puzzles or airplane models are good for smart kids.But if you are not sure what others will like, you can give them "gift certificate cards (授权卡)" from a store. They can get whatever they like with the cards. The cards can be worth US$20 or US$30 ____.Usually parents help the kids buy the gifts that they want. So they can make the right decision.

    Before the parties, kids usually wrap the gifts in colourful paper. It's also fine to use newspaper as gift wrap.So ____to open the gifts? In the West, it's usually while everyone is at the party. The receiver (接受者) tries to say something about each gift - like how lovely it is.