人们常用形象的图式来描述物质世界（）例如：水的电解可表示_爱下问搜题

搜题请搜索小程序“爱下问搜题”

问题选择题

人们常用形象的图式来描述物质世界（　　）

例如：水的电解可表示为：

可见，化学反应前后，下列各项中可能有变化的是（　　）

A．原子的数目

B．分子的数目

C．原子的种类

D．分子的种类

答案

A、反应前后原子的数目不变．

B、分子的数目发生了改变．有的化学变化前后分子的数目不变，例如氢气在氯气中燃烧，反应前后分子数目不变．又如，过氧化氢在二氧化锰的催化作用下生成水和氧气的反应中微粒个数比为2：2：1．反应前后分子数目改变．

C、原子的种类不变．

D、分子的种类一定改变．

故选B．

完形填空

完形填空（共20题，每小题1分，满分20分）
A couple of months ago I was renting a house to work from. I was fairly well set up, but didn't own a lawn mower(割草机) and after a week I __26___ that I would have to find some way to deal with the __27___ grass! Funds were short, and I was on a fairly tight budget which didn't extend(包括)to __28___ lawnmowing company.
I was thinking about this one Sunday as the "Mr. Whippy" ice cream van （大篷车）__29__outside on the street. I hadn't had a Mr. Whippy ice cream for years, and I __30__my coin purse and __31__outside. On the pavement were three young __32__playing. I thought a couple of them may have been from next door, but I was new there and hadn't really __33__anyone yet.
It was a __34__day and I asked them if they'd like an ice cream. "Yes, please," they replied__35___. At that moment a fourth boy _36___them from the neighboring house. Yes, he'd __37__one too!! And there was just enough _38__to cover five ice creams. As I left the van, I heard the lady serving the boys say, "That was a really __39__ thing that lady did for you boys. Don't forget to __40__ her." I smiled as I went inside to carry on working.
I left for work that evening, and didn't __41__until the Tuesday morning. As I came back, I realized something was__42__: Yes, my lawns had been mowed and my gardens had been weeded. I felt this enormous __43__ rush into my heart. I knew my neighbors had done this for me.
This act of __44__not only made a big difference to me, __45_ it was also inspired me to act further in our community.

小题4:A. left B. stopped C started D. passe

A．enthusiastically

判断题

便利店盘点点数结束后，从排行榜里导出的销售量就是盘点期间的销售量。