一个圆柱体和一个圆锥体,半径之比是1:2,高之比是2:5,它们体积之比为( )A

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问题:

一个圆柱体和一个圆锥体,半径之比是1:2,高之比是2:5,它们体积之比为(  )
A.1:5B.1:2C.3:10D.4:5
考点:比的认识
题型:选择题

当往复式压缩机分离罐出现高液位报警,需要排污时必须关闭()罐排污阀,而且排污过程中应始终关闭此阀。

A.一段入口分离

B.二段入口分离

C.一级三相分离

D.厂房外排污

题型:选择题
根据短文内容,从下框A~F选项中选出能概括每段主题的最佳选项,并在答题卡上将该选项涂黑。选项中有一项为多余项。
A. Wash yourself as often as possible
B. Avoid being in hot sun
C. Keep away from smoke and alcohol
D. The importance of skin(皮肤)
E. Have a balanced diet
F. Be sure to have enough water
小题1:_________
When it comes to your skin, there is an important fact that you must keep in mind your skin is the largest organ of your body. Therefore, skin health and protection is crucial. Your skin does everything for you. It can keep your body hydrated and regulate your body’s temperature.
Now, here are some helpful tips for you to protect your skin
小题2:_________
Protection against harmful rays from the sun is one of the most important steps that you need to take. With this in mind it is necessary for you to avoid strong sunlight as often as possible. As for sunscreen you need to buy products that contain UVA-1, UVA-2 and UVB protection.
小题3:___________
Your diet also has a direct impact on the health of your skin. The most important aspect of your diet in relation to the health of your skin is to make certain that you eat a proper amount of food items that contain the proteins and nutrients necessary for cellular maintenance, repair and regeneration.
小题4:__________
Water is also important to the health of your skin. While you certainly have heard it before, it actually is true that you should drink at least eight 8-ounce glasses of fresh water every day. There are many health benefits to be derived from drinking water daily, including maintaining healthy skin.
小题5:_________
Finally, when it comes to the health of your skin today and into the future you should avoid smoking all together. In addition, you should drink alcohol only in moderation. Both smoking and excessive alcohol consumption can negatively impact the health of your skin in significant ways.
题型:选择题

某牛奶生产线上每隔30分钟抽取一袋进行检验,则该抽样方法为①;从某中学的30名数学爱好者中抽取3人了解学习负担情况,则该抽样方法为②.那么①,②分别为______、______.

题型:选择题

桂枝在当归四逆汤中的作用是()

A.助卫阳,解肌发表

B.温通胸阳,通行血脉

C.温中阳,祛寒邪

D.温阳化气行水

E.温经散寒,温通血脉

题型:选择题

简述土压平衡系统的控制原理?

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