胚胎时三个造血阶段是（） A.截然分开，前后相继 B.基本重叠

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问题单项选择题 A1/A2型题

胚胎时三个造血阶段是（）

A.截然分开，前后相继

B.基本重叠

C.互相交替，此消彼长

D.顺序不定

E.某个阶段可以缺失

答案

参考答案：C

解析：胚胎时三个造血阶段不是截然分开的，中胚叶造血期、肝脏造血期和骨髓造血期互相交替，此消彼长。各类血细胞形成的顺序分别是：红细胞、粒细胞、巨核细胞、淋巴细胞和单核细胞。

判断题

自动分拣系统应用于迅速、正确分拣大量物品的情况，现代大型分拣系统的分拣速度每小时可达十几万件。( )

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The Americans believe that anybody can become President of the United States. In a recent Hollywood comedy(喜剧), that is exactly what happens.

Dave Kovic, played by Kevin Kline, is a kind-hearted man who runs a business that finds people jobs. He leads a typical(典型的) American way of life, except for one thing－he looks exactly like the President, Bill Mitchell. In fact, the only thing that makes him different from the nation’s leader is that he is very nice!

The president has started using look-alikes during some public appearances. Dave is offered a chance to “serve his country” by becoming one. However, things go wrong. The President becomes very ill and Dave ends up acting as the President forever.

Director Ivan Reitman, who made the popular and successful comedies like Twins, Ghostbusters and Legal Eagles, could have gone for easy laughs by making fun of the American government. Instead, Dave is an attractive comedy about an ordinary man in extraordinary situations. Kevin Kline gives a double performance as Dave and the President, and Sigourney Weaver is at her best as his First Lady. The love story that develops between her role and Dave is a real classic(经典).

The film is 100% American. However, if you’ve ever felt that anybody could do a better job running the country than the people in power, then you’ll enjoy Dave!

小题1:What is the purpose of the text?

A．To tell the reader about the American government.

B．To discus the Americans’ ideas about the President.

C．To make a comparison between Dave and other films.

D．To introduce a new film to the reader.小题2:Who plays the role of the President in the film?

A．Sigourney Weaver.

B．Kevin Kline.

C．Bill Mitchell.