A:Not giving
B:Not being give
C:Having not give
D:Not having give
下列化学用语正确的是( )
This is Mr White's ________ trip to Beijing. He has been there twice before.
在空气中用弹簧测力计称得某物体重力是8N,在水中称时,弹簧测力计的示数是3N,物体在水中受到的浮力大小是 ____ N.