下列有关玻璃棒在“粗盐提纯”实验中，操作错误的是A．捣碎研细B．搅拌溶解C．引流浊液D．搅拌防溅
利用饱和碳酸钠溶液与酸反应，小科同学制作了如图甲所示的简易酸碱灭火器装置，并进行操作。操作结束后，对瓶中残留液进行如图乙所示的实验。
维护劳动者合法权益的重要保证是（ ） A.依法签订劳动合同 B.保障劳动者主人翁地位 C.建立和谐的劳动关系 D.自觉履行劳动者的义务
Mr Smith had a small shop in a town. There were many beautiful things made of gold in the shop. He often stood at the door and called, “Come and see! Come and buy! I’ll show you beautiful things
根据右图实验装置回答：（甲图温度为25oC左右，乙图温度为10oC左右，黑圆点为种子，暗淡部分为水）[（1）在这6粒种子中，只有_____号种子会萌发，
如图1至图4，⊙均作无滑动滚动，⊙、⊙均表示⊙与线段AB、BC或弧AB相切于端点时刻的位置，⊙的周长为，请阅读下列材料： ①如图1，⊙从⊙的位置出
An important question about eating out is who pays for the meal． If a friend of yours asks you to have lunch with him． You may say something like this, “I’m afraid it’ll have to be some plac
