（）是世界上人口最多的洲，也是电力消费需求最大的洲。 A.欧洲 B.亚洲 C.非洲

在半径为3的圆中，120°的圆心角所对的弧长为______，对应扇形面积为______．

Vitamin D helps bones and muscles grow strong and healthy. Low levels of vitamin D can lead to diseases such as rickets (佝偻病), mainly found in children. The thinning of bone is a common problem as people, especially women, get older.

But more and more research is suggesting that vitamin D might also help prevent many diseases. The easiest way to get vitamin D is from sunlight. The sun’s ultraviolet (紫外线的) rays react with skin cells to produce vitamin D. But many people worry about getting skin cancer and skin damage from the sun. As a result they stay out of the sun. Also, darker-skinned people produce less vitamin D than lighter-skinned people. The amount also decreases in older people and those living in northern areas that get less sunlight.

Not many foods naturally contain vitamin D. Foods high in this vitamin include oily fish and fish liveroils (鱼肝油). Farmed fish have only about one-fourth as much vitamin D as wild fish. Small amounts of vitamin D are found in beef liver, cheese and egg yolks. But most of the vitamin D in the American diet comes from foods such as milk.

Research in the last several years has shown that low levels of vitamin D may increase the risk of heart attacks in men and deaths from some cancers. More doctors are now having their patients tested for their vitamin D levels. But as research continues, some experts worry that if people take too much vitamin D, it might act as a poison. Also, skin doctors warn people to be careful with sun exposure because of the risk of skin cancer.

小题1:The first paragraph is mainly about 　　　　.

A．the muscle diseases

B．the sources of vitamins

C．the importance of health

D．the functions of vitamin D小题2:Which of the following people produce the least amount of vitamin D?______

A．Elderly darker-skinned people.

B．Young lighter-skinned people.

C．Elderly lighter-skinned people.

D．Young darker-skinned people.小题3: People can get the most vitamin D from 　　　　.

A．beef liver

B．cheese

C．wild fish

D．farmed fish小题4:What can we infer from the text?_________

A. Being exposed to sunlight is the safest way to get vitamin D.

B. Lack of vitamin D can make people age quickly.

C. Proper vitamin D levels people need are still not determined now.

D. The vitamin D level is higher in men than in women.

我国现行的法律、法规已有1200多个，每年中 * * 和国务院还要下发100多个新的政策文件。这些法律、法规和文件，已经覆盖了中国社会经济发展的各个方面，如果它们都真正得到了切实的贯彻执行，就会有力地推动中国社会经济健康地发展。因此，( )。

A．应该继续制定更多的法律、政策

B．应该采取措施切实贯彻执行现有的法律、法规和政策

C．应该减少新法律的制定

D．应该加强法律工作

根据《巴黎公约》规定，专利保护实行地域原则和国际联合保护原则。（）

简述污染物质的生物迁徙转化途径。