下列仪器中，能直接在酒精灯火焰上加热的是
A．烧杯
B．试管
C．集气瓶
D． ．
B，蒸发皿．
简述全口义齿的固位原理。
She's having a lot of trouble with the new computer, but she doesn't know whom to _____. [ ]
A. turn to
B. look for
C. deal with
D. talk about
