A:不会下落,因为其上方气体流速增大,压强变小
B:不会下落,因为其上方气体流速增大,压强变大
C:会下落,因为其上方气体流速增大,压强变大
D:会下落,因为其上方气体流速增小,压强变小
如图,在▱ABCD中,已知AD=5cm,AB=3cm,AE平分∠BAD交BC边于点E,则EC等于( )
关于黄土高原水土流失的自然原因,叙述正确的是( )
①土质疏松②植被少③地形平坦④夏季降水集中⑤过垦过牧.
Houses in China's big cities are so unreasonably expensive that generally young couples can't afford _______ without their parents' financial support.
花药离体培养过程中不涉及( )