操作旋转机械时,佩戴下列哪些物品最容易对操作人员造成机械伤害?()
A.口罩
B.围巾
C.手表
参考答案:B
根据句意用括号中动词的适当形式填空,使句子的意思完整、正确。
小题1:The woman put on her hat and_______(go )away.
小题2:He won’t go to the cinema because he________(see) the film.
小题3:Just a minute! My brother_______(wash) his car in the garden.
小题4:While he _______(ride)his bike, he fell off and broke his right arm.
小题5:She said she________(teach )Korean for quite some time.
用手往墙上按图钉,图钉尖的面积很小是为了______对墙的压强,图钉帽的面积比较大是为了______对手的压强.历史上著名的______实验测出大气压的值为______Pa.船闸是利用______的原理工作的.