在单斗铲-汽车开采工艺系统中，台阶的划分方式有哪几种（）。A.水平分层 B.倾斜分层

在一种能使pH试纸变红色的溶液中，下列离子因发生氧化还原反应而不能大量共存的

是

①Ag^＋、Na^＋、Al^3＋、Cl^－　           ②Fe^2＋、NO₃^－、Cl^－、Na^＋　

③K^＋、Mg^2＋、CH₃COO^－、SO₄^2－      ④K^＋、H^＋、SO₃^2－、I^－　 

⑤Na^＋、NO₃^－、SO₄^2－、I^－

A．②⑤

B．①②④

C．②③⑤

D．全部

短文改错（共有10小题；每小题0.5分，满分5分）

下面短文中有10处语言错误。请在有错误的地方增加、删除或修改某个单词。

增加：在缺词处加一个漏字符号（∧）， 并在其下面写上该加的词。

删除：把多余的词用斜线（\）划掉。

修改：在错的词下划一横线，并在该词下面写上修改后的词。

注意：1. 每处错误及其修改均仅限一词。

2．只允许修改10处，多者（从11处起）不记分。

Recently，our school has held the meaningful discussion on whether it is reasonable for middle school students to have classes on weekends．Some of our classmates believe we should have classes on weekends．because we can make fully use of the free time to review the lessons we had learnt．Some others are against the opinion，saying we had better to have a good rest on weekends so that we can work effective during the weekdays．The rest agree with neither of the opinion．They have the view which keeping the balance between work and play are both important for us．They suggest one day of the weekend should used to learn our lessons and during the other day they do something interested or have a rest．

减去－4x等于3x²－2x－1的多项式为（ ）．

A．3x²－6x－1

B．5x²－1

C．3x²+2x－1

D．3x²+6x－1

逾期不交管理费，目前物业公司收取的滞纳金标准是（）。

A、每日千分之三

B、每日千分之五

C、每月千分之三

D、每月千分之五

白居易《画竹歌并引》