If the donor country cannot ensure this, then the aid should be reduced, if not stopped altogether.

参考译文：如果捐赠国不能确保/担保此事，那么援助就要减少/就会减少援助，即便没有完全停下来。

这句话的成分和翻译，用法。

contribute to 什么时候是"导致"的意思，什么时候是“有助于，贡献”的意思？

引导条件状语从句连词：if

主语：the donnor country

位于：can't ensure

宾语：this

主句：then the aid should be reduced, if not stopped altogether

contribute to 详细用法如下所示：

(1)(为…)做贡献 (英文解释：If you contribute to something, you say or do things to help to make it successful.)

The three sons also contribute to the family business. 

这3个儿子也为家族事业做出了贡献。

I believe that each of us can contribute to the future of the world. 

我相信我们每一个人都能够对世界的未来有所贡献。

(2)捐献;捐助;援助 (英文解释To contribute money or resources to something means to give money or resources to help pay for something or to help achieve a particular purpose.)

The US is contributing $4 billion in loans, credits and grants.

美国将提供40亿美元的信贷和赠款。

They say they would like to contribute more to charity, but money is tight this year... 

他们说他们很想捐献更多的钱支持慈善事业，但是今年的钱非常紧张。

(3)vt促成;促使；是导致…的原因之一(英文解释 If something contributes to an event or situation, it is one of the causes of it.)

The report says design faults in both the vessels contributed to the tragedy.

报告说两艘船存在的设计缺陷也促成了这场悲剧的发生。

Stress, both human and mechanical, may also be a contributing factor.  

来自人的和机械方面的压力可能也是一个因素。