搜题请搜索小程序“爱下问搜题”
问题 单项选择题

一直线过点A(2，1，3)，且与直线垂直相交，则此直线的方程是()。

A.A

B.B

C.C

D.D

答案

参考答案：A

解析：

先作一平面过点A，且垂直于已知直线，再求已知直线与此平面的交点，进而可得所求平面的一个方向向量，从而得解

单项选择题

有关横向支撑底座，下述正确的是（）

①一般设置于多用途船舱内两舷舷侧；

②其作用是与横向支撑装置组成一支撑系统以控制舱内下层集装箱可能产生的横向歪斜、倾覆及移动；

③横向支撑底座焊接在舱内两舷舷侧的骨架处。

A.①、②；

B.①、③；

C.①～③；

D.②、③。
查看答案
填空题

Many animals engage in play，but homo sapiens is the only animal (1) have invented sports.Since sports are an invention，a part of culture (2) than an aspect of nature，all definitions of sports are somewhat arbitrary. (3) sports are a human universal found in every known culture or a (4) unique to modern society depends upon one’s definition of sports.Men and (5) have always run，jumped，climbed，lifted，thrown， and wrestled，but they have (6) always performed these physical activities competitively. Although all literate societies seem to (7) contests of one sort or another in which men， and sometimes women， (8) in displays and tests of physical skill and prowess，sports may be (9) defined as physical contests performed for their own sake and not for (10) ulterior end.According to this strict definition，neither Neolithic hunters nor contestants (11) religious ceremonies such as the ancient Olympic Games were engaged in sports. (12) on the stipulation that sports must be performed for their own sake (13) the paradoxical elimination of many activities which are usually thought of as (14) ，such as exercises done for the sake of cardiovascular fitness，races run (15) satisfy a physical education requirement，ball games played to earn a paycheck. (16) definition also means abandonment of the traditional usage in which"sport，"derived (17) Middle English disporter，refers to any light hearted recreational activity.In the. (18) of some 18th- century aristocrats，a game of backgammon and the seduction of (19) milkmaid were both considered good sport，but this usage of the term (20) become archaic.
查看答案