下封层宜采用层铺法表面处治或稀浆封层法施工，下封层的厚度不宜小于（）mm，且做到完全密水。
A、5
B、6
C、8
参考答案：B
小数除法的商都小于被除数．______．
--- How long has your mother ______ Beijing?
--- About two weeks. But she will come back tomorrow.
A．been to
B．been in
C．gone in
D．gone in
