脉冲在探头和界面之间往返2次以上而产生的伪像称为

A．多途径伪像

B．旁瓣伪像

C．混响伪像

D．散射伪像

E．折射伪像

—It's 9 o'clock now. I must go.

—It's raining outside. Don't leave _____ it stops. [ ]

A. when

B. since

C. while

D. until