Invariably the background was the same: dirt and poverty, and very uncomfortable.

肮脏、贫穷，极其不舒适。

Once we get down to the oil, it usually flows to the surface because great pressure,

一旦到达油层，石油就会由于地下巨大的压力流到地面上来，

If we glimpse the unutterable, it is unwise to try to utter it, nor should we seek to invest with significance that which we cannot grasp.

如果我瞥见了只可意会不可言传的事物，企图把它说出来，那上不明智的；对于我们不理解的事物，我们也不应该去赋予它某种意义。

it is quite reasonable to regard the sea floor as the basic form of the crust of the earth,

因此完全有理由把海床看作地壳的基本模壳，

It is a world of red sandy deserts (hence its name----the Red Planet),

红色行星），

Normal people tend to forget this process unless and until they are reminded of it.

衰老的过程，不经提起，正常人容易忘记；一经提醒，才会记起。