They live on the mountain tops where there's little soil,它們生長在土壤不多的山頂上

live on在...生活

I live on the same street as Peter.

我和彼得住在同一條街上。

They are asked to live on campus.

校方要求他們住校。

Occasional morning mists sweep across the high ground.這里偶爾會飄過晨霧

sweep across席卷，橫掃；沖過，迅速掠過

Storms sweep across it and pile up great waves.

風暴襲來會激起巨大的海浪。

The reform bandwagon swept across the country.

改革浪潮席卷全國。

Water is so precious that the tree cannot afford to waste any.這里的水分太珍貴一丁點都不能浪費

afford to付得起, 能承擔

We can afford to overlook minor offences.

我們可以不計較小過。

I can't afford to spend any more on food.

用在食物上的錢，再多一點兒我也花不起了。