【单选题】Play Play is the principal business of childhood,and in recent years research has shown the great importance of play in the development of a human bein9.From earliest infancy. every child needs opport...
A.
he should be allowed to choose his own toys.
B.
he should be given identical toys.
C.
he should be given different toys.
D.
he should be given fewer and fewer toys.
【单选题】听力原文:W: Jim, thank goodness, you've arrived, the class presentation started half an hour ago and I was really desperate. M: I am terribly sorry that I'm late, Jane, This morning has been a real mess, ...
A.
Because there was a traffic jam.
B.
Because he got up late.
C.
Because his apartment is far away from the campus.
D.
Because he missed a bus and had to wait for another one.
【单选题】下图为液压千斤顶的工作原理图。P为压力,h为行程,A为活塞面积,则运动关系式为( )。
【单选题】下图为液压千斤顶的工作原理图。P为压力,W为负载,A为活塞面积,则( )。
【简答题】短语英汉对译 1)原始资料 2)observational research 3)探索性调研
【单选题】---- Did he come back early last night? ---- Yes. It was not yet eight o’clock _______ he arrived home.
【多选题】观察图1-2液压千斤顶工作原理图,设作用在小活塞上的力是F、作用在大活塞上的重物重量为G,小活塞和大活塞的作用面积分别是A 1 、A 2 ,小活塞与大活塞下腔的压力分别是P 1 、P 2 ,选出下面描述正确的选项( )