题目内容：

Scientists around the world have been studying the warming of waters in the Pacific Ocean known as El Nino(厄尔尼诺). The appearance of El Nino is known to affect the weather around the world. Scientists still do not completely understand it. Yet they now find they can use it to tell about the future in different areas of the world.

One example is the work of two scientists at Columbia University in New York, Mark Cane and Gordon Eshel. A scientist of Zimbabwe, Roger Buckland worked with them. They have found that when El Nino appears, Zimbabwe has little or no rain. This means corn crops in Zimbabwe are poor. The last El Nino was in 1991 to 1993. That was when southeastern Africa suffered a serious lack of rain.

The scientists wrote about their recent work in the publication Nature. Their computer program can tell when an El Nino will develop up to a year before it does. They suggest that this could provide an effective early warning system for southern Africa, and could prevent many people from starving.

1.El Nino is known as ___.

A. the changing of the weather in southern Africa

B. the warming of waters in the Pacific Ocean

C. the weather which brings drought(旱灾) to Africa

D. the weather phenomenon (现象)that brings heavy rains to Africa

2.Scientists study El Nino in order that ___.

A. they can provide a kind of early warning to the place that will suffer from drought

B. they can tell why Zimbabwe has little or no rain

C. they can do some research work in this field.

D. they can put all this information into their computers.

3.Which of the following is TRUE according to the passage?

A. Nature is the name of the article written recently by the scientists.

B. Three scientists from the USA work on this subject.

C. Southern Africa suffered a serious drought and many people died from hunger.

D. El Nino has something to do with Zimbabwe’s poor crops.

4.What’s the best title for this passage?

A. Appearance of El Nino is Predictable（可预测的）    B. Drought in Zimbabwe

C. Early Warning System    D. Weather in Africa