A:actually
B:relevantly
C:theoretically
D:absolutely
某一弹簧不挂物体时,长度为12cm,受2N的拉力时,长度为14cm,此时弹簧伸长了____,若受6N的拉力时,弹簧伸长____,此时弹簧长度为____。
600 800 1500 700 900
300 400 300 600 800
和:____ ____ ____ ____ ____
差:____ ____ ____ ____ ____