发明于西汉时期的播种工具是 [ ] A．犁壁 B．水排 C．耧车 D．耕犁

如图所示，一电荷量q=3×10^-5C带正电的小球，用绝缘细线悬于竖直放置足够大的平行金属板中的O点。电键S合上后，当小球静止时，细线与竖直方向的夹角α=37°，已知两板相距d=0.1m，电源电动ε=1.5V，内阻r=0.5Ω，电阻R₁=3Ω，R₂=R₃=R₄=8Ω，g取10m/s²，已知sin37°=0.6，cos37°=0.8。求：

（1）电源的输出功率；

（2）两板间的电场强度的大小；

（3）带电小球的质量。

当初步设计有详细设备清单时，可采用( )编制设备安装工程概算。

A．概算指标法

B．类似工程预算法

C．预算单价法

D．扩大单价法

什么叫变形？

B

Rome-Doctors and medical groups around the world last weekend reacted with strong opposition to the news that an Italian specialist is on the point of cloning the first human baby．　　

Dr．Severino Antinori, who is the head of a hospital in Rome, has been referred to in an Arab newspaper as claiming that one of his patients is eight weeks pregnant （怀孕的）with a cloned baby．　　

Antinori refused to comment on the reports, but in March 2001 he said he hoped to produce a cloned embryo （卵）for implantation within two years．So far seven different kinds of mammals have already successfully cloned, including sheep, cats and most recently rabbits．　　

Doctors showed their doubt and were strongly opposed although they admit that human cloning would finally come true unless there was a world wide ban on the practice．　　

Professor Rudolf Jaenisch of the Whitehead Institute for Biomedical Research at the Massachusetts Institute of Technology said: “I find it astonishing that people do this where the result can be foretold that it will not be a normal baby．It is using humans as guinea pigs．It makes people feel sick．” But Ronald Green, director of the Ethics institute at Darmouth College in the US, said it is unlikely that an eight-week-old pregnancy would lead to a birth．　　

So far all cloned animals have suffered from some different serious disorders, many of them dying soon after their births ．　　

Doctors are opposed to human cloning because they are worried about the welfare of the cloned child if there is one．　　

“There are no benefits of cloned human beings, just harm,”said Dr．Michael Wilks of the UK．

45．What is the doctors’ general attitude to cloning of humans according to the passage?

A．They are against it．                    B．They support it．

C．They welcome it．                          D．They pay no attention to it．

46．Which of the following statements is true according to the passage?

　  A．Doctor Severino Antinori is strongly opposed to cloning human beings．

　  B．Up to now, seven kinds of animals have been cloned, including sheep, cats, humans and rabbits．

　  C．Professor Rudolf Jaenisch is carrying on an experiment on cloning an eight-week-old embryo．

　  D．Ronald Green doubts about the future successful birth of the so-called cloned embryo．

47．Which is the best title for the passage?

　  A．The Success of Cloning Humans           B．The Anger at Cloning Humans

　  C．Failure of Cloning Humans             D．First Cloned Human?

有一承租人向房东租借房屋，租期10个月。租房合同中写明，承租人在租借期内应对房屋损坏负责，承租人为此而以所租借房屋投保火灾保险一年。租期满后，租户按时退房。退房后半个月，房屋毁于火灾。于是承租人以被保险人身份向保险公司索赔。

保险人是否承担赔偿责任？为什么？如果承租人在退房时，将保单转让给房东，房东是否能以被保险人身份向保险公司索赔赔？为什么？