VOA慢速英语:UN Says Food Production Must Rise; How 'Fertilizer Trees' Could Help

短语讲解：

1. One-fourth of all land is described as "highly degraded."

describe as描述为
例句：I hesitate to describe him as really clever.
我不愿说他真的聪明。

2. It calls for greater use of ways that can expand production while limiting damage to ecosystems.

call for需要; 要求
例句：Your plan will call for a lot of money.
你的计划需要许多钱。
limit to (把…)限制在…, 局限于…
例句：Each customer is limited to four tickets.
每人限购四张票。

3. Basically these are trees that can fix nitrogen from the atmosphere and convert them into nitrates for fertilizer, for organic fertilizer, for the soil.

convert into (使)转而变为…
例句：All the bank money was converted into cash.
所有的银行票据都兑换成了现金。

4. We actually got started by about twenty years ago trying to diagnose, to look at, the chief problems within the country, within the region.

look at看, 注视
例句：He looked at me with scorn.
他轻蔑地看了看我。