I _____ to the party _____ at all possible, but I was fully occupied last night. [ ]

A. should have gone; were it

B. could go; if it had been

C. would go; it had been

D. could have gone; had it been

老年患者突然发生寒战、高热、咳嗽、咳痰，痰黏稠、砖红色、胶冻状，引起感染最可能的病原菌是

A．葡萄球菌

B．克雷伯杆菌

C．铜绿假单胞菌

D．流感嗜血杆菌

E．嗜肺军团杆菌