A:①②③④
B:②③
C:③
D:②③④
读经纬网图,回答问题.
— Smart phones are more and more popular now.
— So they are. But they still ________ too much.
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.
下列各句中,没有语病的一句是( )