垫层设在底基层和土基之间，起排水、隔水、防冻、防污等作用。
参考答案：对
Johnny wanted to ride his new bicycle in the street, but his mother told him _____.
A．not to
B．not do it
C．not to do
D．do not
. your rotten idea, we went the long way .
A．Thanks to
B．Due to
C．Owing to
D．Because
