利用轮廓线属性，可以调整轮廓线的（） A.颜色、粗细、长度 B.颜色、长度、粗细

如图所示，有A、B两质量为M= 100kg的小车，在光滑水平面以相同的速率v₀=2m/s在同一直线上相对运动，A车上有一质量为m = 50kg的人至少要以多大的速度（对地）从A车跳到B车上，才能避免两车相撞？

根据下面短文内容，在短文的空格处填上一个恰当的词，使短文完整、通顺。

People usually check whether their keys, wallets and phones are with them___小题1:___ going out. But many people in Chain now have one more important thing to take, a face mask(面罩). They hope that it __小题2:____ protect them from polluted air.

Since January, many cities in China have seen a lot of hazy(雾蒙蒙的)days. In Beijing, ____小题3:___five days in January were free of smog(雾霾). People in Xi’an only saw a blue sky on one day in February. Smog is dirty air that ___小题4:___like fog and smoke.

An official for the Ministry of Environmental Protection told Beijing News that PM2.5 pollution is the main problem with air pollution. PM2.5 refers to pollution with small particles(颗粒) of 2.5 micrometers(微米) or less in diameter(直径).

According to the Chinese Academy of Sciences, ___小题5:_____cars and burning coal(煤) are two major factors(原因) for PM2,5.

Poor air is___小题6:___ for people’s health, especially for children and the elderly. A report from Beijing Children’s Hospital shows that from Jan 5 to 11, half of the patients in the internal medicine department(内科门诊) are there for respiratory(呼吸) problems.

Air problems and environmental protection have become a concern(关切的事) for the whole nation. Premier Wen Jiabao___小题7:____ his last Government Work Report on March 5. the report said that the government should work hard to prevent pollution and give people a ____小题8:____living environment.

It calls on people to make full use of energy and resources and cut down on energy use.

物理性"胖听"应（）

A.废弃

B.限期销售

C.可食用

D.重新消毒后销售

E.重新装罐

甲医院与乙建筑工程公司于2002年5月26日签订建筑工程承包合同，合同约定：由某建筑工程公司为某医院建造门诊大楼，预计2004年5月26日交付验收，验收合格后支付工程款的90%，剩余款项在2005年5月26日前结清。双方按照合同履行了各自的义务。2006年1月12日，该大楼局部墙面出现细微裂缝，后来裂缝渐渐变大，到了2006年3月20日墙皮大片脱落，该医院应在( )之前向乙建筑工程公司提出索赔。

A．2006年5月27日

B．2007年5月27日

C．2008年2月13日

D．2008年3月21日

以下不属于焰熔法合成尖晶石内含物的是（）

A、气泡

B、弧形生长纹

C、助熔剂残余物

D、氧化铝残渣