1.Of the two suggestions ( )is tseful to us,but we should ad

1.Of the two suggestions ( )is tseful to us,but we should adopt them properly
A.both B.either C.neither D.none
我想知道为什么不选C,要选B呢?
2.——Why are our phone bills always so high?
——Well,we make too many phone calls ,so the bills soon ( )
A.add up B come up C.bring up D.pack up
我选的是B,可是add up没有增加的意思啊?为什么选A呢?
3.The problem ( ) at present has something to do with our daily lives.
A.to be discussed B.to discuss C.been discussed D.being discussed
这道题我选的是B,这个就是完全不太明白了~
4.I still remember that morning Kate came to school alone ( )
A.to be upset B.upset C.was upset D.being upset
这个题呢,我选的是D,为什么不选B呢?
5.Our life should be made full use of ( )something meaningful
A.achieving B.achieved C.achieve D.to achieve
我选的是A,也是不太明白的.
这几个是英语的,
CaCO3是不是强电解质?
H2O能不能导电?如果不能的话它为什么算是电解质呢?而且它为什么符合电解质的定义呢?
蒸馏水到底有没有丁达尔效应?
Na2O2为什么算是特殊的氧化物呢?
NH4是不是盐呢?
其实大家也不用全部回答,
还有一个化学的~
氨气溶于水是生成氨水还是一水合氨?
那个打错了,是usefu