常用句型
　　科技文章中经常使用若干特定的句型，从而形成科技文体区别于其他文体的标志。例如It——that——结构句型；被动态结构句型；结构句型，分词短语结构句型，省略句结构句型等。
　　举例如下：
　　It is evident that a well lubricated bearing turns more easily than a dry one.
　　显然，润滑好的轴承，比不润滑的轴承容易转动。
　　It seems that these two branches of science are mutually dependent and interacting.
　　看来这两个科学分支是相互依存，相互作用的。
　　It has been proved that induced voltage causes a current to flow in opposition to the force producing it.
　　已经证明，感应电压使电流的方向与产生电流的磁场力方向相反。
　　It was not until the 19th century that heat was considered as a form of energy.
　　直到十九世纪人们才认识到热是能量的一种形式。
　　Computers may be classified as analog and digital.
　　计算机可分为模拟计算机和数字计算机两种。
　　The switching time of the new-type transistor is shortened three times.
　　新型晶体管的开关时间缩短了三分之二。（或——缩短为三分之一。）
　　This steel alloy is believed to be the best available here .
　　人们认为这种合金钢是这里能提供的最好的合金钢。
　　Electromagnetic waves travel at the same speed as light.
　　电磁波传送的速度和光速相同。
　　Microcomputers are very small in size ,as is shown in Fig.5.
　　如图5所示，微型计算机体积很小。
　　In water sound travels nearly five times as fast as in air.
　　声音在水中的传播速度几乎是在空气中传播速度的五倍。
　　Compared with hydrogen, oxygen is nearly 16 times as heavy.
　　氧与氢比较，重量大约是它的十六倍。
　　The resistance being very high, the current in the circuit was low.
　　由于电阻很大，电路中通过的电流就小。
　　Ice keeps the same temperature while melting.
　　冰在溶化时，其温度保持不变。
　　An object, once in motion, will keep on moving because of its inertia.
　　物体一旦运动，就会因惯性而持续运动。
　　All substances, whether gaseous, liquid or solid ,are made of atoms .
　　一切物质，不论是气态、液态，还是固态，都由原子组成。