it's（带撇号）只能用作itis的缩约形式。"It's" (with an apostrophe) should be used only as a contraction for "it is".用句后括号中的词或词组来回答问题, 注意撇号的位置.Answer these questions, using the words in parentheses. Put the apostrophe in the ri...
Commonly the dolomite crytals form a framework with evenly distributed porosity.通常白云石晶体构成格架,它有均匀分布的孔隙.Locally dolomite and anhydrite are important as cements , together with minor authigenic quartz.在局部地方白云石和硬石膏也是重要的胶结物;还...