这个句子中应该 用 are。因为 a variety of learning materials. 各式各样的 学习材料，是复数 形式。勤学好问 天天进步！
Some countries produce food for export, for example, meat, sugar, or cereals such as wheat and maize. These countries are agricultural countries. An agricultural county needs fertile land and a good climate. A cold, dry climate is not suitable for agriculture....
如果变成陈述句，steel and concrete are used as chief building materials today, 主语一眼就看出是复数steel and concrete （钢筋和水泥是两种物质，是复数概念） . 再说，后面的building materials 也是复数形式。
The full capacity (250 mAh g−1) of the hard carbon is also obtained in Na-ion cells by using the layered P2-type NaxNi0.22Co0.11Mn0.66O2 ... L Wu,D Buchholz,C Vaalma,... - 《Chemelectrochem》 被引量: 19发表: 2016年 Structure Evolution and Electrochemical Performance of Al2...
English for Architecture Unit 1 Building Materials Prestressed concrete is an improved form of reinforcement. Steel rods are bent into the shapes to give them the necessary degree of tensile strength. They are then used to prestress concrete, usually by pretensioning or posttensioning methods. ...
Recent Progress in Materials is an international peer-reviewed Open Access journal published quarterly online by LIDSEN Publishing Inc. This periodical is devoted to publishing high-quality papers that describe the most significant and cutting-edge resea
The factory used 65 percent of the raw materials the rest of which___ saved for other purposes. A . is B . are C . was D . were 扫码下载作业帮搜索答疑一搜即得 答案解析 查看更多优质解析 解答一 举报 答案: D 解析: 考查主谓一致。句意:这家工厂用了 65% 的原材料,剩余的被作为它用。
This variance demonstrates if more or less material is used than expected. When there is more than one input material, the material usage variance can be split into material mix and yield variances. When we talk about the materials ‘mix’ we are referring to the q...
英语翻译Life cycle assessment (LCA) is a technique for assessing variousaspects associated with development of a product and its potentialimpact throughout a product’s life [4].LCA stage includesdefinition of goal and scope,inventory analysis,impact ass
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such...