4____5=20
8____2=6
40____5=8
8____1=8
从力臂的定义上看,力臂是由 ____和 ____共同决定的,它包含了力的两个要素.
It is difficult for us to imagine_____ life was like for slaves in the ancient world.
. ______ news it is! We will have a trip this weekend.
根据以上不完整的统计图提供的信息,解答下列问题: