在人类认识运动的过程中，对自由落体运动的研究，应用了抽象思维、数学推理和科学实验相结合的研究方法，被誉为人类思想史上最伟大的成就之一，标志着物理学真正的开始．采用这一研究方法的科学家是（   ）

下列所给的图象中能反映作直线运动的物体在2秒末回到初始位置的是（   ）

太阳中蕴藏无比巨大的能量，下列说法正确的是（  ） 

从下面方框中选出与下列各句中画线部分意思相同或相近，并能替换画线部分的选项。

My mother usually goes to work at ____ about 7:30 in the morning,
John is a clever boy. He ____ does well in all the subjects,
Dave's father was ill two days ago, so he had to ____ take care of him at home.
Last night, Tom was not ____ in. He went to a movie with his friends.