2. 表示不可避免性或肯定性
这时must—般只用于肯定句,主要是推测现在或将来必然发生的事情,可译为 “必然”、“必定”等。如:
* The power output of a transformer must be less than the power input because of unavoidable losses in the form of heat.
变压器的输出功率必然小于输入功率,因为热的损耗无法避免。
* For some centuries before there was experimental proof, it was believed that the speed of light must be finite.
在有实验证明以前的好几个世纪,人们就已相信光的速度必定是有限的。
* At any instant, the difference between the transistor-capacitor current and the output current must be the supply current.
在任何瞬间,晶体管一电容电流与输出电流之差必定是电源电流。
must后也可跟“have +过去分词”结构,表示对过去已发生事情的推測,可译 为“一定”、“一定已经”等。如:
* They must have removed these fuses.
他们一定已经更换了这些保险丝。
* An electric timer must have been wired into this system.
这个系统一定是安装了电子定时器。
责任编辑:admin