1. It is quite reasonable to regard the sea floor as the basic form of the crust of the earth, with, superimposed upon, it the continents, together with the islands and other features of the oceans.
    因此完全有理由把海床看作地壳的基本模壳，上面附加着大陆以及岛屿和海洋的其他形态。

2. And we think that the earth´s crust is very uneven indeed.
    我们于是认识到地表确实是起伏不平的。

3. Although scientists still cannot predict earthquakes, they are learning a great deal about how the large plates in the earth's crust move, the stresses between plates, how earthquakes work, and the general probability that a given place will have an
    尽管科学家们仍无法预测地震，但对地壳中的大板块如何移动，板块间的压力如何，地震如何发生，某地区发生地震的一般概率为多少，他们正了解得越来越多。

4. On the very outside of the earth is a bumpy crust of rock and soil.
    地球的最外层是由岩石和土壤构成的凹凸不平的硬壳，