Then he and his wife entered a five-kilometer race.

　　后來(lái)，他和他的妻子參加了5千米的比賽。

　　You get that out of 1 cubic kilometer of seawater.

　　你能從一千立方米海水中得到這么多。

　　The mine is some 840 meters deep and 6.5 kilometer long.

　　這個(gè)礦區有840米深，6.5千米長(cháng)。