问题 单项选择题 A2型题

潜伏性感染时,患者在发病间歇期()

A.可以分离出病毒

B.不能分离出病毒

C.间歇分离出病毒

D.不能分离出病毒也不能测出抗体

E.可以分离出病毒但不能测出抗体

答案

参考答案:B

解析:有些DNA病毒可致潜伏感染,以人类的单纯疱疹病毒、水痘-带状疱疹病毒最为常见。隐性感染或显性的急性期感染后,病毒基因长期存在于一定组织和细胞内,并不能产生有感染的病毒体,与机体细胞保持一定程度的相对平衡。当受生理或病理因素的影响,机体抵抗力下降时,病毒能被激活而出现临床症状。病毒在发病间歇期可潜伏于组织或细胞内,在此期间通常不能分离出病毒,但在病人血清中可以测出抗体。这一点是潜伏性感染与慢性感染及慢发病毒感染不同之处。

单项选择题
阅读理解

Seth DeBolt is a plant scientist at the University of Kentucky US. He and other scientists wanted to find a source of fuel that poor people in rural areas of developing countries could use to make electricity.

The United Nations Development Program says a billion and a half people have no electricity. A billion others have an undependable supply.

Professor DeBolt went on a study trip to rural Indonesia. He saw that there was very little waste in the use of agricultural products. Everything that farmers grew was used for something. Even the remains of fruit that people did not eat were fed to chickens.

Little waste meant there was little that could be used for fuel. Growing a separate fuel crop would take land away from food crops. That was something Professor DeBolt did not want to do.

DeBOLT said, "The people at most risk with respect to energy poverty, typically they're the same people who have food insecurity issues as it is. And then any change in availability would be most damaging to that group of people."

But he found one item that was in plentiful supply and would not create competition between food and fuel. Coconut shells are generally thrown out. Yet Professor DeBolt says it has an "excellent" heating value. All someone needs is a way to release that energy.

DeBolt says he and his team see possibilities for coconut power. "Coconuts are growing here and these are the areas where there is possibility for energy poverty to be eased at least in part by these small-scale production systems."

The researchers say these systems could provide as much as thirteen percent of the energy needs of a country like Indonesia. Other tropical countries with large crops of coconuts and similar fruit could benefit, as well.

But DeBolt says this is not a perfect solution. There are technical questions, like how to safely deal with the dangerous waste produced in the process. And there needs to be money to get these projects started.

小题1:Professor DeBolt went on a study trip to rural areas of developing countries to      .

A.help farmers make full use of waste

B.seek certain materials to make electricity

C.persuade farmers to grow more coconuts

D.find a suitable place to carry out the experiment小题2:DeBolt thought it was not a good idea to grow fuel crops because      .

A.there are plenty of coconuts

B.local farmers have no interest in it

C.it would make food problems worse

D.fuel crop has little use for local farmers小题3:The last two paragraphs mainly tell us that coconut power      .

A.needs further experiments and efforts

B.can help solve energy problem perfectly

C.will cause technique and money problems

D.has drawn Indonesia's government attention小题4:What might be the best title for the passage?

A.Make Full Use Of Coconuts

B.Make Power From Coconuts

C.A Perfect Solution

D.Food And Energy Problems