显示多生牙、埋伏牙的位置、牙根病变、腭裂间隙等情况，要做（） A.X线头影测量 B.

如图所示某种遗传病的家族系谱图，请问5号与6号所生孩子正常的几率是多少

A．3/4

B．1/4

C．2/3

D．1/3

女患，30岁，因 * * 大流血2小时来院。该患平素月经规律，5-6/30日型，现闭经40天。孕3产0。（人流1、宫外孕1、葡萄胎1），末次妊娠一年半前为葡萄胎。近一个月轻度咳嗽并少量咯血。既往曾有肺结核史。妇科检查外阴、 * * 、宫颈正常，子宫稍大、略软、活动好，无压痛，左附件区可及鸭卵大囊性肿物，右附件软。辅助检查血β-hCG6ng/ml

下列病史中对诊断最有帮助的是（）

A.肺结核史

B.宫外孕史

C.人流术

D.葡萄胎史

E.闭经史

卵巢癌的治疗原则是()

A．外科治疗

B．化疗

C．放疗

D．免疫治疗

E．以手术和化疗为主的综合治疗

Believe it or not, optical illusion can cut highway crashes.

Japan is a case in point. It has reduced automobile crashes on some roads by nearly 75 percent using a simple optical illusion. But stripes, called chevrons, painted on the roads make drivers think that they are driving faster than they really are, and thus drivers slow down.

Now the American Automobile Association Foundation for Traffic Safety in Washington D.C. is planning to repeat Japan’s success. Starting next year, the foundation will paint chevrons and other patterns of stripes on selected roads around the country to test how well the patterns reduce highway crashes.

Excessive(too great) speed plays a major role in as much as one fifth of all fatal traffic accidents, according to the foundation. To help reduce those accidents, the foundation will conduct its tests in areas where speed-related hazards (danger) are the greatest curves, exit slopes, traffic circles, and bridges.

Some studies suggest that straight, horizontal bars painted across roads can initially cut the average speed of drivers in half. However, traffic often returns to full speed within months as drivers become used to seeing the painted bars.

Chevrons, scientists say, not only give drivers the impression that they are driving faster than they really are but also make a lane appear to be narrower. The result is a longer lasting reduction in highway speed and the number of traffic accidents.

The advantage of chevrons over straight, horizontal bars is that the former（）

A. can keep drivers awake

B. can cut road accidents in half

C. will look more attractive

D. will have a longer effect on drivers

展览会满意度调研工作是为了宣传