Some problems concerning groups are best attacked by using graphs.

In this section we present a brief but systematic discussion of functions and their graphs.

本节我们要简单而系统地讨论函数及其图象.

The track snaked perilously upwards.

这条小道蜿蜒而上，很危险。

She had spent years trying to track down her parents.

她已经花了好多年时间试图追寻父母的下落。

They left the car and struck out along the muddy track.

他们下了车，然后开始沿着泥泞的小路往前走。

He galloped the horse along the track.

他沿着跑道策马疾驰.

The track star outran all of his competitors.

那位径赛明星比他所有的竞争对手跑得都快.

It is our responsibility to put them on the right track.

我们有责任帮助他们走上正道.

Our horses plodded down the muddy track.

我们的马沿着泥泞小路蹒跚而行。

She branched off down the earth track.

她改变路线，沿着土路走了下去。

He has a proven track record in marketing.

他有可靠的销售业绩记录。

Alluvial soils usually grow the best crops.

淤积土壤通常能长出最好的庄稼。

Such plants could grow in the world's worst soils without costly help.

这类植物用不着投资就能在世界上最差的土壤里生长.

Molybdenum deficiency is found when legumes are grown on acid soils.

在酸性土壤上种植豆科作物时常发现缺钼.

Each climatic environment places its own stamp upon the soils developed there.

每一种气候环境,对该地发育的土壤都能留下自己的痕迹.

Irrigation timing is important due to light rather shallow soils.

由于土壤轻松,土层又浅,及时灌溉是很重要的.

Fruit trees will not tolerate wet soils during the growing season.

在生长季,果树不耐土壤过湿.

The soils have a rusty red tint.

那里的土壤呈锈红色.

Less chemical gets into the sub-soil which is particularly important with the light, tropical soils.

进入底土的化学物质会减少，这对土质松软的热带土壤而言尤为重要。

The universe seems to be rapidly expanding its component galaxies moving ever farther apart.

宇宙似乎在膨胀,它的组成部分――星系互相离得越来越远.

Other galaxies are placed irregularly in space.

其它星系不规则地位于太空中.