The elderly ______ good care of in public places like supermarkets and airports; they are likely to get lost.

A．can have been taken

B．ought to be taking

C．must be taken

D．should take

为使固定桥充分发挥咀嚼功能，首先需要的是（）

A.良好的固位、稳定

B.缺隙区牙槽嵴丰满

C.基牙稳固、支持力强

D.恢复缺失牙的解剖形态

E.设计合理