whence from which whereby by which wherein in

whence: (= from which), （不常见）从句中的谓语一般 是省去的 whereby: (= by which)（不常见） wherein: (= in which)（不常见） Ohm’s law can be written as(写成) V=IR where V represents(表示) voltage, I—current and R— resistance. Electromagnetic(电磁的) induction(感应) is the means(方 法) whereby nearly(几乎) all the world’s electric power(电力) is produced(产生).

In the electron tube(电子管), the negative(负的) electrode (电极) is heated(加热) to the point(程度) where it emits(发射) electrons(电子). These equations(式子) are special(特殊的) cases(情况) where x and t are both zero(零). The maximum(最大的) height(高度) is reached(到达) at a time when the vertical(垂直的) velocity(速度) component(分量 ) has decreased(降) to zero.

In the next chapter(章), we will see the reasons(理由) why different(不同的) sources(光源) emit(发射) different types of spectrum(光谱). The load(负载) is the place where the signal(信号) leaves( 离开) a circuit(电路). A second area(领域) wherein the weighted(加权的) property(性质) is useful is in numerical(数字的) display(显示).

The researchers(研究人员) made great progress(进步 ) in the early(早的) 1970’s, when they discovered(发现) that oncogenes(致癌基因) are inactive(不活跃的) in normal(正常的) cells(细胞).