A:直线AB上
B:直线BC上
C:直线AC上
D:△ABC内部
—Why are you standing(站立), Alice?
—I can't see the blackboard(黑板 ) clearly(清楚地) . Two tall boys are sitting _____________ me.
—How long has Mr Wang worked in the factory?
— 15 years.
“一堆沙子是松散的,可是它和水泥、 石子、 水、 混合后,比花岗岩还坚韧。”这句话告诉我们( )