Only after they had discussed the matter for several hours _______a decision.

　　A they reached        B did they reach     C they reach     D do they reach

一位二尖瓣狭窄患者，最常见的早期症状为

A．劳力性呼吸困难

B．阵发性夜间呼吸困难

C．咯血

D．端坐呼吸

E．声音嘶哑