由原方程，得
(3x-1)2=94
开平方，得
3x-1=±32，
解得x1=56，x2=-16．
The last plane___ , they had to stay in the hotel for another night.
A．left
B．havingleft
C．havingbeenleft
D．beleaving
对提升信号都有哪些基本要求？
