—It's a fine day today. Shall we go swimming?

—_______  But we need to be home before six o'clock. [ ]

A. Have a nice time!

B. Not at all.

C. You are right.

D. Good idea!

行人工流产术时，负压吸引器吸管进出宫颈管时应注意( )

A．降低负压
B．加大负压
C．关闭负压
D．控制负压
E．保持原有负压