题目内容

【题目】The number of children losing both parents to Aids ______ also expected to rise.

A. was B. is C. are D. were

【答案】B

【解析】

试题分析:考查时态和谓语动词的单复数形式。该句中主语:The number of children losing both parents to Aids宾语:expected to rise.主语是一个事物——因艾滋失去双亲的孩子的数量。这里的数量是看做一个整体,所以用单数的谓语动词。根据语境来看,该句是陈述句语气,描述客观事实,所以用一般现在时。句意:因为艾滋病失去双亲的儿童数目有望上升。故选B。

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【题目】Far from the land of Antarctica, a huge shelf of ice meets the ocean. At the underside of the shelf there lives a small fish, the Antarctic cod.

For forty years scientists have been curious about that fish. How does it live where most fish would freeze to death? It must have some secret. The Antarctic is not a comfortable place to work and research has been slow. Now it seems we have an answer.

Research was begun by cutting holes in the ice and catching the fish. Scientists studied the fish’s blood and measured its freezing point.

The fish were taken from seawater that had a temperature of -1.88°C and many tiny pieces of ice floating in it. The blood of the fish did not begin to freeze until its temperature was lowered to -2.05°C. That small difference is enough for the fish to live at the freezing temperature of the ice-salt mixture.

The scientists’ next research job was clear: Find out what in the fish’s blood kept it from freezing. Their search led to some really strange thing made up of a protein never before seen in the blood of a fish. When it was removed, the blood froze at seawater temperature. When it was put back, the blood again had its antifreeze quality and a lowered freezing point.

Study showed that it is an unusual kind of protein. It has many small sugar molecules (分子) held in special positions within each big protein molecule. Because of its sugar content, it is called a glycoprotein. So it has come to be called the antifreeze fish glycoprotein, or AFGP.

【1】Why can the Antarctic cod live at the freezing temperature?

A. The seawater has a temperature of -1.88°C.

B. It loves to live in the ice-salt mixture

C. A special protein keeps it from freezing.

D. Its blood has a temperature lower than -2.05°C.

2What does the underlined word “it” in Paragraph 5 refer to?

A. A type of ice-salt mixture.

B. A newly found protein.

C. Fish blood.

D. Sugar molecule.

3What does “glyco-” in the underlined word “glycoprotein” in the last paragraph mean?

A. sugar B. ice C. blood D. molecule

4What is the best title of this passage?

A. Discovery of the AFGP.

B. A special fish living in Antarctica.

C. The ice shelf around Antarctica.

D. Protection of the Antarctic cod.

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