A good way to pass an exam is to work hard every day in the year。3 You may fail in an exam if you are lazy for most of the year and then work hard only a few days before the exam．If you are taking an English exam, do not only learn rules of grammar．21·cn·jy·com

Try to read stories in English and speak in English whenever you can．A few days before the exam, you should start going to bed early．Don’t stay up late at night studying and learning things．Before you start the exam, read carefully over the question paper．4 Try to understand the exact meaning of each question before you pick up your pen to write．When you have at last finished your exam, read over your answers．Correct the mistakes if there are any and make sure that you have not missed anything out．

A）根据短文内容简要回答问题。

小题1:Learning rules of grammar is enough to pass the English exam, isn’t it?

小题2:What should you do a few days before the exam?

B）将短文中划线的句子译成汉语。

小题3:                                                                     

小题4:                                                                   

C）请给短文拟一个适当的标题。

小题5:                                                                   

碳酸钙和硫酸钙都是钙的重要化合物，它们在生产生活中都有着广泛的应用．甲、乙两组同学分别对碳酸钙的制备、硫酸钙的性质进行了以下探究，请你参与并完成对有关问题的解答．

（1）甲组使用大理石（含少量的Fe₂O₃杂质）等物质制备碳酸钙的实验流程如图1：

①溶解大理石时，用硝酸而不用硫酸的原因是______．

②上述流程中，“分离”得产品所包含的实验操作依次为：过滤、______、______．

③“滤液A”中除H⁺离子外，还含有的阳离子是______；检验该阳离子的实验方法是：取少量滤液A与______在试管中混合、加热充分反应，将湿润的红色石蕊试纸（或pH试纸）靠近试管口，观察现象即可．

（2）乙组对某硫酸钙晶体（xCaS0₄•yH₂0）加热分解的有关反应进行探究．他们取6.52g该晶体进行加热，加热过程中，固体质量随时间的变化情况如图2所示．又知t₅～t₆时间段内固体质量减轻的原因是产生了两种气体，反应的化学方程式为：2CasO₄

①加热时，该晶体开始发生化学变化的时间是______（填“t₁”、“t₃”或“t₅”）．

②t₄～t₅时间段固体的化学式为______．

③t_l～t₂时间段固体发生反应的化学方程式为______．