简单归纳仿真的主要作用。

边长相等的下列两种正多边形的组合，不能作平面镶嵌的是[ ]

A.正方形与正三角形

B.正五边形与正三角形

C.正六边形与正三角形

D.正八边形与正方形

根据短文内容，从短文后的选项中选出能填入空白处的最佳选项，并在答题卡上将该项涂黑。选项中有两项为多余选项。

Eyesight plays a very important role in our daily life. Every waking moment, the eyes are working to see the world around us. Over forty percent of Americans worry about losing eyesight, but it's easy to include steps into our daily life to ensure healthy eyes. Here are five suggestions for a lifetime of healthy eyesight:

· Schedule yearly exams. 小题1:       Experts advise parents to bring babies 6 to 12 months of age to the doctor for a careful check. The good news is that millions of children now can have yearly eye exams and following treatment, including eyeglasses.

· Protect against UV rays (紫外线). Long-term stay in the sun creates risk to your eyes. No matter what the season is, it's extremely important to wear sunglasses.

  小题2:   

Give your eyes a break. Two-thirds of Americans spend up to seven hours a day using computers or other digital products.  小题3:   Experts recommend that people practice the 20/20/20 rule: every 20 minutes, take a 20-second break and look at something 20 feet away.

· 小题4:   As part of a healthy diet, eat more fruits and vegetables each day. Vitamins (维生素) C and E help protect eyesight and promote eye health.

·  Practice safe wear and care of contact lenses (隐形眼镜). Many Americans use contact lenses to improve their eyesight. While some follow the medical guidance for wearing contact lenses, many are breaking the rules and putting their eyesight at risk.   小题5:   Otherwise, you may have problems such as red eyes, pain in the eyes, or a more serious condition.

A．Eat your greens.

B．Eye care should begin early in life.

C．They can properly protect your eyes.

D．Stay in good shape by taking more vitamins.E. Parents usually don’t care about their own eyesight.

F. Always follow the doctor’s advice for appropriate wear.

G. This frequent eye activity increases the risk for eye tiredness.

肝硬化代偿期的体征是（）

A．黄疸

B．皮肤紫癜

C．肝大、质偏硬

D．腹壁静脉曲张

E．男性 * * 发育

《内经》所谓“阴阳之征兆”，是指

A．男女
B．天地
C．左右
D．水火
E．上下

以色列和巴勒斯坦国都位于（）地区。

A、东亚

B、西亚

C、南亚

D、北亚