—_________ weather it is! We can't go boating on the Xuanwu Lake.
—Don't worry. Let's go to the Science Museum instead.
A：What good
B：How good
C：How had
D：What bad
使x+1有意义的x的取值范围是( )
两个顽皮的孩子逆着自动扶梯行驶的方向行走，从扶梯的一端到达另一端，男孩走了100秒，女孩走了300秒．已知在电梯静止时，男孩每秒走3米，女孩每秒走2米．则该自动扶梯长____ 米．
