某环境监测站每隔一段时间抽取雨水试样,测定其pH,数据如下: 测定时间/min0

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问题:

某环境监测站每隔一段时间抽取雨水试样,测定其pH,数据如下:

测定时间/min012345
pH4.94.74.54.44.44.4
下列有关说法不正确的是

A.雨水的酸性持续减小

B.雨水的酸性一段时间后趋于稳定

C.酸雨对农作物的生长会产生一定的影响

D.工业废气中的硫和氮的氧化物是形成酸雨的主要因素

考点:室内空气污染大气污染、改善大气质量水的净化与处理水体污染、爱护水资源
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     I have been using the Internet since I was five years old, when my dad first sat me down in front of a

computer and connected me the World Wide Web.

     I've always felt like a master(主人) of the Internet world. AOL Instant Messaging, MSN, Gmail,

Facebook. Myspace-I've got it all under control. I thought there was nothing more to it besides checking my e-mail and wasting my time, until I was introduced to electronic commerce(e-commerce): business on

the Internet.

     Some online business are run from one- room home offices. Others have hundreds of employee(雇员)

spread across five different continent. Have you ever heard of Amazon. com, Yahoo. com?

     My friends often said they got cheap textbooks off Amazon.com, or had a good deal(交易)on Steve Madden boots that were on sale at SteveMaden.com. Unfortunately for me, I continued my

"e-commerceless" Web-surfing, unaware(不知道)of all the deals I was missing out on.

     That is, of course, until my sister finally sold the idea to me.

     "Why are all these packages(包裹)arriving in the mail for you, Katy?" I asked her one day. Strange

envelopes had been put on our doorstep for weeks now, each one always addressed to my sister; and we all know little sisters should never be getting more mail than their elders!

     "Oh, it's the things I ordered online!" she answered. I watched speechlessly as she opened them. There was no way our parents were letting her spend that much money- online or off!

     "How much did all of this coat?"

     "Oh, only about $15 in all!" She said excitedly. "Everything on eBay is on sale! It's way better than

going to the mall."

     I felt as if there had been a store right in my backyard that I had never walked into! That week, I ordered a used Spanish textbook for my summer course online for 10 percent of the publishing price. A few

days later, I bought an iPod protector and a book or two via the wonderful eBay.com.

1. From the first two paragraph we can conclude that the author          .

A. had noexperience using computers

B. had no idea of what e-commerce is

C. only used the Internet to check e-mail

D. thought surfing the Internet was a waste of time

2. The writer didn't find out about e-commerce until          .

A. he stopped web-surfing

B. he visited a store in his backyard

C. his friends told him about the online deals they made

D. his sister explained the packages she got by mail

3. We can infer from the last paragraph that the author           .

A. has begun to enjoy online shopping

B. loves the big store in her backyard

C. feels she is a true master of the Internet

D. never enjoyed shopping that much

4. What's the purpose of the article?

A. To make an online shopping ad.

B. To do business on the Internet.

C. To tell the readers how he begins online shopping.

D. To advise people not to do online shopping

题型:选择题

扭矩型高强度螺栓连接副按每批号随机抽()套,复验紧固轴力的平均值和变异系数。

A.3

B.5

C.8

D.10

题型:选择题

分布距离大约在1000公里可能属于( )。

A.局域网

B.城域网

C.广域网

D.互联网

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矿渣水泥可用于耐热混凝土工程中但不宜用于有抗渗要求的混凝土工程中。

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与人交往应具备哪些良好品质?

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