鉴别下列各组物质,选用括号内的试剂或方法,不合理的是[ ]
A.纯碱和食盐(稀盐酸)
B.硬水与软水(肥皂水)
C.羊毛与涤纶(灼烧)
D.氧化铜与木炭粉(观察颜色)
答案:D
The second Sunday of May is ________ Mother’s Day. It’s ________ special day for children
to show their love for their mothers.
A.a;the
B.the;a
C.不填;a
D.不填;the
()是保持物质化学性质的最小微粒。
A.原子
B.分子
C.离子
D.质子