— We’ll visit the Summer Palace_______ there is a heavy rain tomorrow.

— OK! Boating on the lake must be great fun.

A．unless

B．since

C．as soon as

D．if

男性，24岁，2天前肛门周围持续性跳痛，皮肤硬结红肿，并有局部压痛，可能出现了（）。

A．肛裂

B．内痔

C．外痔

D．直肠脱垂

E．肛门周围脓肿