Rivers in Japan, however, have smaller and steeper drainage areas, making these rivers less navigable, because their waters are flowing more steeply down to the sea.

然而，日本的河流流域面积更小、更陡，导致这些河流不太，为它们的水流向大海的坡度更大。

Bump is a small hill or small increase in the road, and dip is a small hole or a small decrease in the road or the street or the freeway or wherever it is that you are traveling.

Bump 是小山丘或道路的小坡度，而 dip 是道路、街道或高速公路或您行驶的任何地方的小坑或小坡度。