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

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

A．if

B．as soon as

C．unless

D．since

下列不是慢性肺源性心脏病的并发症的是（）

A.心力衰竭

B.酸碱平衡失调及电解质紊乱

C.心律失常和肾衰竭

D.休克与弥散性血管内凝血

E.肺性脑病和上消化道出血