[单项选择]A Caterpillars chewing on its leaves B Wasps laying eggs on its leaves C Pesticides sprayed on its leaves D Knives cutting its stalk

[简答题] leaves

[填空题]Leaves show different colors other than green in the fall because the carotenoids and anthocyanins are then______.

[填空题]By the time he leaves university his parents (spend)（）more than 10, 000 dollars on his education.

[单项选择]HIV Vaccine Feat Leaves More Questions Than Answers
Only hours after HIV vaccine researchers announced the achievement of a milestone that has eluded them for a quarter of a century, they began plotting their next steps—and coming back to reality. Their ultimate goal, halting the spread of AIDS, remains far in the future. A Thai and American team had announced early Thursday in Bangkok that they had found a combination of vaccines that provided modest protection against infection with HIV, offering the first proof of principle that the deadly disease could be tamed by teaching the immune system to recognize the virus and defeat it. Scientists around the world hailed the achievement.
But by Thursday afternoon, the initial wave of joy had given way to the recognition that many questions will have to be answered before researchers can produce a vaccine that will reliably shield people from HIV. For starters, it could take years to figure out the biological mechanisms that pr
A. scientists have made certain achievements in HIV vaccine
B. HIV vaccine has been proved successful ultimately
C. HIV vaccine has been proved useless
D. HIV has already been decoded and defeated

[单项选择]What does the woman want to be after she leaves school
A. A musician.
B. A clerk.
C. A vet.

[单项选择]Walking through the dry leaves on his way home, Pat thought of what a bad day in school it had been. But every day was a bad day for him; he and the school did not like each other. But now that he was in the forest, Pat began to feel more like his usual self. He stopped to look at the quick moving stream of water called the Totopotomy. This little river was named for a man Pat liked, Totopotomy chief of the friendly Paumunkey Indians. He had heard stories about boys caught by the Paumunkeys who, when they were free, did not want to go home. Pat could understand how they felt. They did not have to go to school; they lived in the fresh air, and went fishing and hunting. How wonderful that must be!
The gentle sounds of a bird singing could be heard through the trees. Pat looked up, and tried to make the same sound. Uncle Langloo had told him to try and learn the language of the birds, and he was trying. Pat wanted to be like his uncle in every way. Langloo Win- ston was a hunter who
A. want to be like his uncle in every way
B. try to make the sounds of a bird singing
C. like to go to school
D. go to school across the forest

[单项选择]
How long will they wait till the train leaves
A. 22 minutes.
B. 32 minutes.
C. 12 minutes.
D. 2 minutes.

[单项选择] With its common interest in lawbreaking but its immense range of subject matter and widely-varying methods of treatment, the crime novel could make a legitimate claim to be regarded as a separate branch of literature, or, at least, as a distinct, even though a slightly disreputable, shoot of the traditional novel. The detective story is probably the most respectable (at any rate in the narrow sense of the word) of the crime species. Its creation is often the relaxation of University dons, literary economists, scientists or even poets. Fatalities may occur more frequently and mysteriously than might be expected in polite society, but the world in which they happen, the village, seaside re- sort, college or studio, is familiar to us, if not from our own experience, at least in the news- paper or the lives of friends The characters, though normally realized superficially, are as recognizably human and consistent as our less intimate associates. A story set in a more remote environ
A. they enjoy writing these stories
B. the stories are often in fact very instructive
C. detective stories are an accepted branch of literature
D. the creation of these stories demands considerable intelligence

[单项选择]A. Its texture. B. Its size.
C. Its preservation. D. Its shape.