下列关于离子的说法,正确的是[ ]
A.离子都是带电的原子
B.离子是构成物质的最小微粒
C.在化学变化中离子不能再分
D.有些物质直接由离子构成,有些物质却是由原子直接构成的
答案:D
用所给词的适当形式填空,每词仅用一次。
visit two education little serious
小题1:We should exercise at ________ three or four times a week.
小题2:This is an ___________movie.You can’t miss it.
小题3:Dalian is the best city for __________because it’s the most beautiful.
小题4:If you don’t take these shows too_______,they are fun to watch.
小题5:My parents allow me to play computer games ______a week.
含有个级、万级和亿级的数,最多是( )位数,最少是( )位数。