1 date back to追溯到
2 be to be at rest: 是静止的意思，比如：The earth seems to be at rest,but in fact it rotates on its axis and revolves around the sun.地球好像是不动的，但实际上，它绕轴自传并围绕太阳运行。
be at rest 在休息
3 it followed that... 因此，于是得出这样的结果了，是很好的承上启下的连接句
4 传统观点tradition，传统观点也认为可以用hold这个动词
5 no one until sb, 可以翻译成sb是第一个怎么样的人
6 it is said that承上启下，如果直接说Galileo demonstrated that有些生硬，加上这句就暗含了上面的实验表明的意思
7 比萨斜塔 the Leaning Tower of Pisa
8 let go of 释放，很形象
if you let go of a ball on a slope that drops by one meter for every ten meters you go along, ... 斜度的表示
9 a lead weight: 吊锤
10 做实验：perform /conduct/carry out ... experiment
11 作用act on: In Galileo’s experiments, as a body rolled down the slope it was always acted on by the same force (its weight)...
12 this showed that ..., rather than ..., as was previously thought.
13 be proportional to 与...成比例的
14 the acceleration is twice as great if the force is twice as great.
15 The acceleration is also smaller the greater the mass of the body.
16 a body of twice the mass； half the acceleration
17 the laws would still hold. 定律仍然成立
18 our apparently commonsense notions 我们的常识观念
19 Nevertheless, Roemer’s achievement, in not only proving that light travels at a finite speed, but also in measuring that speed,was remarkable – coming as it did eleven years before Newton’s publication ofPrincipia Mathematica
句子结构很值得分析，coming as可以翻译成要知道
20 on account of the mass of the sun: on account of 考虑到
21 block out： the sun's light is blocked by the moon
22 be in progress: the First World War was in progress
23 it was not until 1919 that...
24 with the advent of
25 be of considerable practical importance
26 put an end to/get rid of
