A:尼龙绳
B:汽车轮胎
C:纯棉T恤
D:塑料薄膜
如图,△ABC中,D,E两点分别在AB,AC边上,且DE∥BC,如果ADAB=23,AC=6,那么AE的长为( )
如图所示带电导体,已知其表面的电场强度EA=100N/C,EB=1N/C,点电荷q在电场力的作用下第一次由A点由静止释放到运动到无限远处;第二次由B点由静止释放到无限远处.两次的末速度大小之比为( )
It's generous __ ___ them to donate money to UNICEF. They think it important _____ them to help poor children go to school.