1.The boy d____ the cake into six pieces.

1.The boy d____ the cake into six pieces.
2.I wasn't used to the life in the city in the b___,but later,I liked living here.
3.The g____ effect is becoming a serious problem nowadays.
4.Don't spit here.Please pay attention to your b_____.
5.In Sweden it is against the l____ to hit a child.
（ ）I think it's ______ useful advice,so I will always remeber it.
A.a B.an C.不填 D.the
个人认为填C或D.因为adcive是不可数n..