It rains very heavily in this area, which has _______ annual rainfall of 7,000 mm, _______ ideal

environment for forests．[ ]

A．the; an

B．an; 不填

C．an; an

D．不填; the

女性，7岁。易疲劳、剧烈活动气促1年余来诊。查体：胸骨左缘2～3肋间可闻Ⅱ级SM。超声心动图检查示房间隔紧邻上腔静脉处回声脱失20mm。

诊断初步考虑（）

A.Ⅰ孔型房间隔缺损

B.原发孔房间隔缺损

C.混合型房间隔缺损

D.下腔型房间隔缺损

E.上腔型房间隔缺损