锁肛痔好发于哪个年龄段()
A.30岁以上
B.40岁以上
C.50岁以上
D.60岁以上
E.任何年龄
参考答案:B
___early for his date, Mark spent time reading the newspaper
A.Arriving
B.Having arrived
C.Arrived
D.To arrive
下列可用于排地下水和地面水的排水设施是( )。
A.暗沟
B.排水沟
C.蒸发池
D.渗沟