净空变化速度小于0.2mm/d、拱部下沉速度小于（）mm/d时，说明围岩达到基本稳定。
A、0.1
B、0.15
C、0.2
D、0.25
参考答案：B
Few people know the fact ______ was not until 1936 that basketball became a regular part of the Olympic Games.
A．it that
B．that it
C．that
D．it
什么是易燃液体？什么叫可燃液体？
