美国太空总署(NASA)为探测月球是否存在水分,于2009年10月9日利用一支火

题型:选择题

问题:

美国太空总署(NASA)为探测月球是否存在水分,于2009年10月9日利用一支火箭和一颗卫星连续撞击月球. 据天文学家测量,月球的半径约为l 800 km,月球表面的重力加速度约为地球表面重力加速度的1/6,月球表面在阳光照射下的温度可达127℃,而此时水蒸气分子的平均速率达2 km/s,下列说法正确的是

A. 卫星撞月前应先在原绕月轨道上减速

B. 卫星撞月前应先在原绕月轨道上加速

由于月球的第一宇宙速度大于2 km/s,所以月球表面可能有水

D. 由于月球的第一宇宙速度小于2 km/s,所以月球表面在阳光照射下不可能有水

考点:万有引力定律
题型:选择题

我国去南极考察的时间,最好选择在我国的什么季节?[ ]

A.夏季

B.春季

C.冬季

D.秋季

题型:选择题

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。

Business is the organized approach to providing customers with the goods and services they want. The world business also refers to an organization that provides these goods and services. Most business seek to make a profit(利润)—that aim to achieve income that is more than the costs of operating the business. 小题1:  Commonly called nonprofits, these organizations are primarily nongovernmental service providers. 小题2: 

Business management is a term used to describe the techniques of planning, direction, and control of the operations of a business. 小题3:  One is the establishment (制定)of broad basic policies with respect to production; sales; the purchase of equipment, materials and supplies; and accounting. 小题4: The third relates to the establishment of standards of word in all departments. Direction is concerned primarily with supervision(监管)and guidance by the management in authority. 小题5: 

A.The second aspect relates to the application of these policies by departments.

B.However, some businesses only seek to enough to cover their operating costs.

C.Control includes the use of records and reports to compare actual work with the set standards for work.

D.Examples of nonprofit business top management and operative management.E. Planning in business management has three main aspects.

F. In the theory of business management, organization has two main aspects.

G. In this connection there is the difference between top management and operative management.

题型:选择题

驻马店市中招实验考试时,莉莉同学抽到了一道题,以下是莉莉完成实验的操作过程的示意图。实验完毕后她没有得到满分,她失分的操作是(    )。

A.①②

B.②③

C.②④

D.③⑤

题型:选择题

淬火一般为了增加工件的硬度和耐磨性。

题型:选择题

斐林试剂测定还原糖含量时,反应滴定要控制在()分钟内完成。

A.1

B.2

C.3

D.4

更多题库