如图所示,小球以v0=6 m/s的速度从中间滑上光滑的足够长斜面,已知小球在斜面

题型:计算题

问题:

如图所示,小球以v0=6 m/s的速度从中间滑上光滑的足够长斜面,已知小球在斜面上运动时的加速度大小为2 m/s2,问小球速度大小为3 m/s时需多长时间?(小球在光滑斜面上运动时,加速度大小、方向不变)

考点:匀变速直线运动的速度与时间的关系
题型:计算题

Do you still get free plastic bags from the supermarkets? Things have changed.

China has banned(禁止)free plastic bags in  shops and supermarkets,and people have to pay for using plastic bags. The rule started on June 1st. It came because our country tried to make less litter. Making super-thin plastic bags has also been banned.

The Chinese once used about 3,000,000,000 plastic shopping bags a day,and they have caused pollution of the environment. The bags have become a main cause of plastic pollution because they are easy to break and people throw them away here and there. So the Chinese people are encouraged to bring their own bags for shop ping.

What kind of shopping bag is the best to bring? Some students in Chongqing have a good idea. They make their own shopping bags. They use old clothes to make cloth bags,and send them to their parents as presents. They also ask their parents and friends to use cloth bags instead of plastic ones. They think it is their duty to protect the environment.

根据短文内容,选择最佳答案。

小题1: People in China have to         now.

A.throw plastic bags here and there

B.collect plastic bags in the street

C.pay for using plastic bags at shops and supermarkets

D.use free plastic bags at shops and supermarkets小题2: China made this rule because plastic bags were bad for the        .

A.environment

B.families

C.shops

D.supermarkets小题3: The Chinese people are encouraged to bring          for shopping.

A.no bags

B.free plastic bags

C.their own bags

D.super-thin plastic bags小题4:Some students in Chongqing        .

A.ask their parents to make cloth bags

B.make cloth bags themselves

C.pick up plastic bags everywhere

D.buy cloth bags for their parents小题5:What’s the main idea of this article?

A.Making super-thin plastic bags has been banned in China.

B.The bags have become a main cause of plastic pollution.

C.Some students in Chongqing begin to make their own shopping bags.

D.To protect the environment,free plastic bags have been banned in China.

题型:计算题

TCP/IP参考模型的最底层是()。

题型:计算题

诊断二尖瓣狭窄的特异性指征是()

A.左心房扩大

B.心房颤动

C.第一心音亢进

D.心尖部舒张期隆隆样杂音

E.P2分裂

题型:计算题

在渤海某轮自东向西穿越冷锋,通常风向将由()。

A.S~SW转N~NW

B.S~SW转E~SE

C.E~SE转S~SW

D.N~NW转E~SE

题型:计算题

生活饮用水的PH值应在()范围内。

A.5-7

B.4-5

C.6.5-8.5

更多题库