2. When the virus drops on any surface, it will live for at least 12 hours.

If the internal structure of a part is complex, the internal surfaces of it will result in too many hidden lines. In this case, a sectional view should be used to reveal the internal features of the part.（）

Although the model looks good on the surface, it will not bear close ______.

A．scrutiny

B．temperament

C．symmetry

D．contamination

Although the model looks good on the surface, it will not bear close ______.

A．disposition

B．contamination

C．scrutiny

D．symmetry

Although the model looks good on the surface, it will not bear close______.

A．disposition

B．contamination

C．scrutiny

D．symmetry

Passage 2

Scientists have found the first evidence that briny water flowed on the surface of Mars as recently as last summer, a paper published on Monday showed, raising the possibility that the planet could support life.

Although the source and the chemistry of the water is unknown, the discovery will change scientists’ thinking about whether the planet that is most like Earth in the solar system could support present day microbial life.

The discovery was made when scientists developed a new technique to analyze chemical maps of the surface of Mars obtained by NASA’s Mars Reconnaissance Orbiter spacecraft.

They found telltale fingerprints of salts that form. only in the presence of water in narrow channels cut into cliff walls throughout the planet’s equatorial region. The slopes appear during the warm summer months on Mars, then vanish when the temperatures drop. Scientists suspected the streaks were cut by flowing water, but previously had been unable to make the measurements.

Mars Reconnaissance Orbiter makes its measurements during the hottest part of the Martian day, so scientists believed any traces of water, or fingerprints from hydrated minerals, would have evaporated.

Also, the chemical-sensing instrument on the orbiting spacecraft cannot home in on details as small as the narrow streaks, which typically are less than 16 feet wide. But Ojha and colleagues created a computer program that could scrutinizeindividual pixels. That data was then correlated with high-resolution images of the streaks. Scientists concentrated on the widest streaks and came up with a 100 percent match between their locations and detections of hydrated salts.

The Iceman

On a September day in 1991, two Germans were climbing the mountains between Austria and Italy. High up on a mountain pass, they found the body of a man lying on the ice. At that height (10,499 feet, or 3,200 meters), the ice is usually permanent, but 1991 had been an especially warm year. The mountain ice had melted more than usual and so the body had come to the surface.

It was lying face downward. The skeleton (骨架) was in perfect condition, except for a wound in the head. There was still skin on the bones and the remains of some clothes. The hands were still holding the wooden handle of an ax and on the feet there were very simple leather and cloth boots. Nearby was a pair of gloves made of tree bark (树皮) and a holder for arrows.

Who was this man? How and when had he died? Everybody had a different answer to these questions. Some people thought that it was from this century, perhaps the body of a soldier who died in World War I, since several soldiers had already been found in the area. A Swiss woman believed it might be her father, who had died in those mountains twenty years before and whose body had never been found. The scientists who rushed to look at the body thought it was probably much older, maybe even a thousand years old.

With modem dating techniques, the scientists soon learned that the Iceman was about 5,300 years old. Born in about 3300 B. C. , he lived during the Bronze Age in Europe. At first scientists thought he was probably a hunter who had died from an accident in the high mountains. More recent evidence, however, tells a different story. A new kind of X-ray shows an arrowhead still stuck in his shoulder. It left only a tiny hole in his skin, but it caused internal damage and bleeding. He almost certainly died from this wound, and not from the wound on the back of his head. This means that he was probably in some kind of a battle. It may have been part of a larger war, or he may have been fighting bandits. He may even have been a bandit himself.

By studying his clothes and tools, scientists have already learned a great deal from the Iceman about the times he lived in. We may never know the full story of how he died, but he has given us important clues to the history of those distant times.

The body of the Iceman was found in the mountains mainly because

A．two Germans were climbing the mountains.

B．the melted ice made him visible.

C．he was lying on the ice.

D．he was just on a mountain pass.