重点讲解：
1. be conditional on
以…为条件的；
eg. Their support is conditional on his proposals meeting their approval.
他们的支持是以他的提议得到他们的批准为条件的。
eg. His agreement to buy our house was conditional on us leaving all the furniture in it.
他同意买房子，条件是我们要把家具都留在屋内。
2. not only...but also...
不但……而且；
eg. Keats'poems are not excellent, but also perfect in form.
济慈的诗不但思想内容极好，而且形式完美。
eg. This will save not only labour but also money.
这不仅省事而且省钱。
3. speed up
（使）（某一过程或活动）加快；
eg. We are aimed to speed up our delivery times.
我们正力争加快交货时间。
eg. They help speed up the development process.
这可以帮助加速开发过程。
4. account for
（数量或比例上）占；
eg. Petrochemicals today account for one fourth of all the chemicals made, in ten years this amount is expected to double.
石油化工产品现在已占所有化学制品的四分之一，十年后预计这个数目还要加倍。
eg. Together they account for less than five per cent of the population.
他们总共占不到总人口的5%。
5. refer to
指的是；
eg. The Western Hemisphere refers to North and South America.
西半球是指南北美洲。
eg. These nouns refer to an unfilled or empty space.
这些名词指未填的或空白的地方。
