单项选择题
A.or B.and C.but D.with
A. A lot of patients need a second operation. B. Doctors are not well trained to ensure successful operations. C. Demands for hip replacement exceed the number of surgeons. D. Replacement operation is becoming too expensive in U. S. hospitals.
A. are always alone in the country B. can easily get away from crowds and traffic C. get trapped in popular beauty spots D. can be lost in such countryside