为了保证保修任务的完成，发包人可以从应付承包人工程款内预留质量保修金，其金额及比例可

对于草地里的青草来说，下列属于非生物因素的是                   （   ）

A．温度

B．老鼠

C．狗尾巴花

D．蛇

填写单词。

1. My sister used to eat _____ and she often had a toothache.

2. Fred doesn't like to study and he often _____ a lot of trouble at school.

3. When Mike thinks of his little cat's          , he feels very sad.

4. To our _____, he won first place in the school spoken English contest.

5. We shouldn't _____ natural resources because there aren't many left.

6. Mark tried his best to solve the problem all by ______.

7. Tina is quite successful. Her father takes ______ in her.

8. She is ______ with everyone. Whenever you ask her questions, she would like to reply.

9. Jimmy ______ to be thin, but now he is very fat.

10. My English is poor. I made a _____ to learn English well this term.

11. They both show _____ in the beautiful music.

12. Kate is very shy. She used to be afraid of ______ in front of our class.

13. You must pay ______ to your pronunciation.

14. It's not right to ______ too much time on computer games.

15. How do you feel when you see the national flag of China in space? It makes me feel excited and ______.

16. If you want to be healthy, it's _____ for you to eat some vegetables and fruit.

A、B两物体叠放在光滑水平面上，对A物体施加一水平变力F，F-t关系图象如图所示．两物体由静止开始运动，且始终相对静止．则（　　）

A．t₀时刻，两物体间的摩擦力为零

B．t₀时刻，两物体的速度方向开始改变

C．2t₀时刻，两物体的速度为零

D．t₀-2t₀时间内，两物体间的摩擦力逐渐减小

根据《食品卫生法》规定，食品主要包括( )。

A．原料食品

B．治疗性物品

C．成品食品

D．药物食品

E．保健品

Arsenic, a naturally occurring poison and carcinogen found in ground water, is ply linked to adult-onset diabetes, U. S. researchers said on Tuesday. Odorless, tasteless, colorless and easily soluble in water or wine, arsenic has long been a feared poison. A heavy dose is detectable in a corpse, but researchers say small amounts of arsenic may sicken people gradually.

Dr. Ana Navas-Aeien and colleagues at Johns Hopkins University in Baltimore found a " relatively p " association between commonly found levels of arsenic in urine and type 2 diabetes in a study of American adults. " It seems there is maybe no safe level of arsenic. " Navas-Acien said in a telephone interview. " Worldwide it’s a huge problem, " she said. " As water becomes a scarce resource. the situation becomes even more serious. "

Arsenic raises the risk for cancers of the bladder, lung, kidney, skin and, possibly, the pros tate, Navas-Acien said. The 20 percent of nearly 800 study participants who had the most arsenic in their bodies, a tolerable 16. 5 micrograms per liter of urine, had 3. 6 times the risk of developing late-onset diabetes than those in the bottom 20 percent, who had 3 micrograms per liter. Levels of arsenic were 26 percent higher in people with late-onset, or type 2, diabetes than those without the disease, the study found.

The U. S. government sets a limit for drinking water at 10 micrograms of arsenic per liter, which is exceeded in the water consumed by 13 million Americans who mostly live in rural areas that rely on wells to bring up ground water, the researchers wrote in the Journal of the American Medical Association. Arsenic contaminates drinking water for millions of people in Bangladesh, parts of Central Europe, Chile, Argentina and the western United States, where ground water is the source of drinking water and the land has higher concentrations of arsenic.

Overall, 7. 8 percent of Americans are believed to have diabetes, although some do not know it. At least 90 percent of cases are the type 2 variety, in which the body loses its ability to use insulin properly. Navas-Acien said arsenic may play a significant role in diabetes incidence, but it is difficult to say how much. Arsenic can accumulate in the body, and can ruin the body’s ability to use insulin and perform the vital task of converting blood sugar into energy. Normally, insulin fits into cells via molecular doorways called receptors, which in turn signal the cell to move glucose inside, but arsenic enters the cell and somehow blocks the activity. Seafood is another source of arsenic, but the organic form found in shellfish and some fish has a carbon molecule attached and poses no risk to health, she said.

According to the passage, arsenic contains（）

A. smell

B. taste

C. poison

D. color