There are many varieties and grades of paper materials, and whilst it is fairly easy to spot the varieties, it is far more difficult to spot the grades.

纸张材料有许多品种和等级，虽然很容易分辨它们的种类，但要分辨它们的等级就困难得多了。

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The plan has good chances of success, since sweet potato is a staple of the region's diet and agriculture, and the varieties currently grown contain little beta-carotene.

该计划成功的机会很大，因为红薯是该地区的主食和主要农产品，而且目前种植的品种几乎不含胡萝卜素。

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A season in the field will help determine which, if any, of the varieties are ready for commercialization.

在田里试种一季，有助于决定哪种水稻（如果有的话）适宜商业推广。

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He says a few varieties of cassava can resist brown streak, but these are not the kinds Africans like.

VOA: special.2010.06.08

Iser We may or may not have the lecture on Iser, but on Tuesday we'll be getting into the varieties of formalism and first we'll take up the American New Criticism.

我们将来可能有一讲会详细介绍，但下周二我们讲各种形式主义,首先是美国新批评。

耶鲁公开课 - 文学理论导论课程节选

so it helps one individual to understand just the varieties of language and

这能帮一个人了解不同的语言，还有

五年级 - SpeakingMax英语口语达人

Twelve of the varieties, which are all prefixed "Ben", are currently in commercial production.

BBC: Blackcurrants

That's why some coffee-industry experts favor expanding the varieties of coffee being cultivated and crossbreeding plants to strengthen them.

WSJ: The Indiana Jones of Coffee

Over five days, more than 70 speakers and performers explored the varieties of openness and its uses in science, politics, technology, government and the arts.

CNN: What if you could make anything you wanted?