The doctor suggested that the old man ______ an operation without delay. [ ]

A. must have

B. to have

C. had

D. have

可摘局部义齿的铸造支架不能就位的原因是（）

A.基牙的倒凹大；

B.支架铸造收缩；

C.基牙向缺牙区倾斜；

D.基牙有支点；

E.固位体选择不当。