搜题请搜索小程序“爱下问搜题”
问题 选择题

质量为m的小球从距地面高为h的水平桌面飞出，小球下落过程中，空气阻力可以忽略.小球落地点距桌边水平距离为S，如图所示，关于小球在空中的飞行时间t以及小球飞出桌面的速度V0，下面判断正确的是（   ）

A．t=

B．t=

C．v0=

D．v0=s/

答案

答案：D

题目分析：解决本题的关键是知道平抛运动在水平方向和竖直方向上的运动规律，以及知道分运动和合运动具有等时性．小球在下落过程中做平抛运动，在水平方向上做匀速直线运动，在竖直方向上做自由落体运动．设飞行时间为t，则在竖直方向上有：，解得：，故AB错误；设平抛运动的初速度大小为v0，在水平方向上有：，解得：，

单项选择题 A1/A2型题

健康相关行为是指（）

A.与疾病相关的行为

B.与健康和疾病有关的行为

C.促进健康的行为

D.致病性行为

E.与健康相关的行为
查看答案
阅读理解

根据短文内容, 从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

A serious problem for today’s society is who should be responsible for our elderly and how to improve their lives.It is not only a financial problem but also a question of the system we want for our society. 小题1:

First,employers should take the responsibility for their employees.小题2: But when a company must take life-long responsibility for its employees,it may suffer from a commercial disadvantage due to higher employee costs.

 小题3: This means each person must  save during his working years to pay for his years of retirement.This does not seem a very fair model since some people have enough trouble paying for daily life without trying to earn extra to cover their retirement years.This means the government might have to step in to care for the poor.

In addition, the government could take responsibility for the care of the elderly.This could be financed through government taxes to increase the level of pensions.Furthermore,some institution should be created for senior citizens,which can help provide a comfortable life for them.  小题4:

The government can seldom afford to care for the elderly,particularly when it is busy trying to care for the young.

One further solution is that the government or social organizations establish some working places especially for the elderly where they are independent.

小题5:Therefore,it is reasonable to expect that some combination of these options may be needed to provide the care we hope to give to our elderly generations.

A．Every coin has two sides

B．To sum up,all these options have advantages and disadvantages.

C．I would like to suggest several possible solutions to this problem.

D．It’s unfair to let the government to share all the responsibilities.E.      To make this possible,a percentage of profits should be set aside for this purpose.

F.      Another way of solving the problem is to return the responsibility to the individual.

G.  Unfortunately,as the present situation in our country shows,this is not a truly practical answer.
查看答案