1 . Without ________ (引力) there would be no air and no sound of any kind. (根据汉语提示单词拼写)
您最近一年使用:0次
2 . The force of_______________ (重力)pulls things towards the earth's centre. (根据汉语提示单词拼写)
您最近一年使用:0次
3 . An apple falls down because of________ (重力).(根据汉语提示单词拼写)
您最近一年使用:0次
4 . __________ (万有引力) is the force that causes things to drop to the ground. (根据汉语提示单词拼写)
您最近一年使用:0次