词组及地道用法：

1、date back to 

▶Our present ideas about the motion of bodies date back to Galileo and Newton.

延伸

▶ ...-A perpetual struggle to discover how the University works that goes back to the earliest civilizations.

2、pure thought

▶...one could work out all the laws that govern the universe by pure thought.

自己造句：▶It's impossible to mediate the dilemma by pure thought.

3、lead weight 吊锤

▶If one drops two bodies that don't have much resistance,such as two lead weights,...

4、be proportional to 

proportional      properly related in size or degree or other measurable characteristics; usually followed by `to'

▶This states that a body will accelerate,or change its speed,at a rate that is proportional to the force.

5、have something doubled

▶Thus the force between two bodies would be twice as strong if one of the bodies(say, body A)had its mass doubled.

6、have+次数+something

▶One of the bodies had twice the mass,and the other had three times the mass..

7、for instance

▶For instance,one playing Ping-Pang on the train,...

8、accord with

▶...it didn't accord with his idea of an absolute God.

9、given和provided

given：介词，其后只能跟名词

▶Given his age,he did it quite well.

provided:连词或形容词，形容词意为“提供的”

▶...,provided they used a good clock.

▶Please put your litter in the bin provided.

▶To get these features working you first have to install the software provided.