如图所示为竖直平面内的直角坐标系。一个质量为m的质点,在恒力F和重力的作用下,从

题型:选择题

问题:

如图所示为竖直平面内的直角坐标系。一个质量为m的质点,在恒力F和重力的作用下,从坐标原点O由静止开始沿直线OA斜向下运动,直线OA与y轴负方向成θ角(θ<45°),不计空气阻力,则以下说法正确的是(    )

A.当F=mgtanθ时,质点的机械能守恒

B.当F=mgsinθ时,质点的机械能守恒

C.当F=mgtanθ时,质点的机械能一定增大

D.当F=mgsinθ时,质点的机械能可能增大也可能减小

考点:机械能守恒定律
题型:选择题
Many parents want their children to be famous(著名的) one day. But do children have the same       
A new     , Hi, Ke’ai, is on at Beijing Children’'s Art Theatre(剧院). It tells the story of a boy called Ke’ai. His parents would like him to become a painter(画家) or a     one day. So they teach him to     and to play the violin, but Ke’ai doesn't enjoy these activities. Then one day Ke’ai’s parents see Mo Yan won an award (奖)for his works, and they want him to be a writer, too
     do they want me to be someone else?” Ke'ai asks and says, “I        want to be myself.”
The play(话剧) shows us that it is        for parents to learn to understand their children. It helps parents to       what kids really want to be in the future.
Young audiences(观众)enjoy the story, and also the     in the play(话剧). There are two songs in the play. One of them, Ke’ai’s Song, is very easy to learn, so the audiences can sing the song on their way home     the play!
小题1:
A.jobsB.dreamsC.storiesD.hobbies
小题2:
A.songB.filmC.playD.cartoon
小题3:
A.writerB.teacherC.sportsman D.musician(音乐家)
小题4:
A.paintB.writeC.runD.drive
小题5:
A.HowB.WhyC.WhenD.Where
小题6:
A.onlyB.seldomC.neverD.sometimes
小题7:
A.easy B.importantC.interestingD.exciting
小题8:
A.talk aboutB.worry aboutC.think aboutD.talk of
小题9:
A.lightB.clothesC.skillD.music
小题10:
A.beforeB.inC.afterD.at
题型:选择题

依据现行《建筑设计防火规范》的规定,下列的防烟楼梯间可不设置防烟设施的有:()

A.当防烟楼梯间前室采用敞开的阳台进行防烟时

B.当防烟楼梯间的合用前室采用敞开的凹廊进行防烟时

C.当防烟楼梯间前室内有不同朝向且开口面积大于2㎡的可开启外窗时

D.当防烟楼梯间的合用前室内有不同朝向且开口面积大于3㎡的可开启外窗时

题型:选择题

VBA表达式IIF(0,20,30)的值为______。

A.20

B.30

C.10

D.50

题型:选择题

从动件等加速等减速运动规律的凸轮机构在整个行程的中间,加速度()。

A.为零

B.不变

C.有限突变

D.无穷大

题型:选择题

患者赵某,男性,20岁,体型瘦高。举重物后突感左胸闷、出冷汗,呼吸困难。查体:神志清楚,面色苍白,口唇发绀,呼吸30次/分,右上肺叩诊呈鼓音,听诊呼吸音消失,心率110次/分,律齐。

治疗包括()

A.氧疗

B.抗生素治疗

C.给予适当镇静剂

D.抽气减压

E.给予强心剂

F.严格卧床休息

G.抗凝治疗

H.给予利尿剂

I.给予呼吸兴奋剂

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