氯乙烯精馏形式是（）精馏。
A.常压
B.加压
C.减压
D.先减压后增压
参考答案：B
Snow is rare in this area. You can hardly see any snow, ________ it is winter.
A．ever since
B．now that
C．even though
D．even so
里外酥脆型的菜肴，要用约140℃的油温______加热原料。
A．短时间
B．长时间
C．持续地
D．多次
