笔记

1 Friction makes the work put into a machine greater than the useful work accomplished by it.
2 By power is meant the speed,or rate,of doing work.
3 Our semiconductor industry came into being at the end of the 1950s.
4 the voltage across the registor is measured in volts.
5 substituting Eq7 into Eq8,we get a=b.
6 work equals(is equal to) force multiplied by distance.
7 this equipment has quite a few advantages all its own.
8 By observing the effect of a new drug on the patients,we can see its efficiency of the cure.
9 Icon is almost as good a conductor as aluminium.
10 On being heated,the air in the bottle will expand.
11 Air exerts pressure in every direction.
12 The hotter the body,the more energy it radiates.
13 The ability of some elements to give off radiations is referred to as radioactivity.
14 To do all this,a sound knowledge of computer science is required.
15 The voltage across this capacitor is a few hundredths of a volt.
16 Of the first four chapters, Chapter 3 is the most important.
17 it is necessary to find how long a time it takes to solve this equation.
18 Medium-sized computers now perform as large computers not long ago.
19 Let it be required to find out this angle(假设需要求出这个角度来).
20 The farther away the target is,the longer (time)it takes for the echo to return(目标越远，回波返回所需的时间就越长).

有用的句型:
1 be of great help to
2 only one fifth what it is now
3 half the final output
4 four times thicker than
5 the difference between these two values is 13 parts in a million.
6 From its definition as the ratio of distance to time,
7
8