负压吸引器吸痰的压力是多少()
A.小于100mmHg
B.100~200mmHg
C.300~400mmHg
D.大于400mmHg
E.200~300mmHg
参考答案:C
According to the art dealer, the painting ______ to go for at least a million dollars.
A.is expected
B.expects
C.expected
D.is expecting
下列说法中不正确的是( )
A.用柠檬酸、果汁、白糖、水、小苏打自制汽水
B.被雨水淋湿的自行车,先用干布擦净后才能用带油的布擦
C.宝石中由于含有某些金属离子,才使它们变得更加绚丽多彩
D.喝了汽水后常常会打嗝,说明气体的溶解度随着压强的减小而减小