搜题请搜索小程序“爱下问搜题”
问题 选择题

关于质点的位移和路程，下列说法正确得是（　　）

A．路程是标量，等于位移的大小

B．质点做单向直线运动时，路程等于位移的大小

C．位移是矢量，位移的方向即为质点运动的方向

D．位移的大小比路程小

答案

A、路程是标量，大小等于物体运动轨迹的长度，是标量．质点的位移是从初位置指向末位置的有向线段，是矢量．故A错误．

B、只有做单向直线运动时，路程等于位移的大小，故B正确．

C、位移是矢量，是从初位置指向末位置的有向线段，不一定与质点运动方向相同．故C错误．

D、当物体做单向直线运动时，路程等于位移的大小，故D错误．

故选B．

判断题

PBMS系统中的业务负责人可以查询其辖内客户经理维护客户的产品使用信息。（）
查看答案
单项选择题

The following questions present a sentence, part of which or all of which is underlined. Beneath the sentence, you will find five ways of phrasing the underlined part. The first of these repeats the original; the other four are different. If you think the original is best, choose the first answer; otherwise choose one of the others.

These questions test correctness and effectiveness of expression. In choosing your answer, follow the requirements of standard written English; that is, pay attention to grammar, choice of words, and sentence construction. Choose the answer that produces the most effective sentence; this answer should be clear and exact, without awkwardness, ambiguity, redundancy, or grammatical error.

Health Department statistics demonstrate that children reading high on glucose with family histories of diabetes are twice as likely as the general population to develop diabetes.（）

A. reading high on glucose with family histories of diabetes

B. with high glucose readings whose families have a history of diabetes

C. with high glucose readings and who have a diabetic history in the family

D. having high glucose readings and also having histories of diabetes in their family

E. with a history of diabetes running in the family and with high glucose readings
查看答案