编辑点评: 研习GRE作文考试的优秀范文不仅可以学到有用的词汇和句子,更能从中学习逻辑的构建方式和作文框架的结构等内容,这里为大家提供GRE的范文,希望对同学们的备考有所帮助。
Topaz is a hard, transparent mineral. It is a compound of aluminum, silica, and fluorine. Gem topaz is valuable. Jewelers call this variety of the stone precious topaz . The best-known precious topaz gems range in color from rich yellow to light brown or pinkish red. Topaz is one of the hardest gem minerals. In the mineral table of hardness, it has a rating of 8, which means that a knife cannot cut it, and that topaz will scratch quartz.
The golden variety of precious topaz is quite uncommon. Most of the world s topaz is white or blue. The white and blue crystals of topaz are large, often weighing thousands of carats. For this reason, the value of topaz does not depend so much on its size as it does with diamonds and many other precious stones, where the value increases about four times with each doubling of weight. The value of a topaz is largely determined by its quality. But color is also important: blue topaz, for instance, is often irradiated to deepen and improve its color.
Blue topaz is often sold as aquamarine and a variety of brown quartz is widely sold as topaz. The quartz is much less brilliant and more plentiful than true topaz. Most of it is variety of amethyst: that heat has turned brown.
国际英语资讯:UKs border systems not ready in no-deal Brexit, warns parliament committee
英首相承诺推动英国在非洲投资
国际英语资讯:Ecuador FM says difficult to restore diplomatic ties with Venezuela in short-term
体坛英语资讯:IOC to continue cost-cutting efforts for Olympic host cities: Bach
国际英语资讯:EU will be able to overcome Brexit: Austrian president
体坛英语资讯:Dortmund overpower resilient Augsburg 4-3 in German Bundesliga
国际英语资讯:Thailand can learn from Chinas development model:Thai deputy PM
To Develop Green Cities 发展绿色城市
国际英语资讯:Abbas aide slams U.S. envoys remarks as intervention of internal Palestinian affairs
体坛英语资讯:Kenyas Zakayo of Kenya to skip Diamond League meeting
国际英语资讯:Sudan, Egypt agree on coordination over regional, intl issues
Why students learn English? 我们为什么学英语
美国将不派高官参加中国投资博览会
美特勤局截获送往克林顿、奥巴马的可疑包裹
国际英语资讯:Vietnam detects transnational marijuana smuggling ring
国际英语资讯:Feature: Chinese hospital ship Ark Peace wins praise from Tongans
国际英语资讯:Germanys Merkel lauds Ghana for peace and stability
国际英语资讯:Kenya, Britain vow to deepen trade, investment ties
体坛英语资讯:Croatias international Rebic pens extension at Frankfurt
国际英语资讯:Iranian foreign minister arrives in Pakistan for 2-day visit on ties
体坛英语资讯:Basilashvili shocks del Potro in China Open final
澳大利亚或禁止曾泄露大量机密的前美国军人曼宁入境
国际英语资讯:EU has profound disagreements with U.S. on trade policy: EU trade commissioner
澳洲新政府周二宣誓就任
体坛英语资讯:Mark Williams wins 2018 Snooker World Open
体坛英语资讯:Head coach Breitenreiter extends at Hannover
国际英语资讯:2 dead, 3 missing after boat capsizes in southeastern Nepal river
美墨达成新贸易协定
国际英语资讯:Russian Defense Minister criticizes Polands plans to deploy U.S. division
美国佛州电子游戏锦标赛中发生枪击
不限 |
英语教案 |
英语课件 |
英语试题 |
不限 |
不限 |
上册 |
下册 |
不限 |