检验某氯代烃中的氯元素,下列操作合理的是 A.取氯代烃少许,加入硝酸银溶液,看是

题型:选择题

问题:

检验某氯代烃中的氯元素,下列操作合理的是

A.取氯代烃少许,加入硝酸银溶液,看是否出现白色沉淀

B.取氯代烃少许,与氢氧化钠溶液共热后加入硝酸银溶液,看是否出现白色沉淀

C.取氯代烃少许,与氢氧化钠共热后加入盐酸酸化,然后加入硝酸银溶液,看是否出现白色沉淀

D.取氯代烃少许,与氢氧化钠共热后加入硝酸酸化,然后加入硝酸银溶液,看是否出现白色沉淀

考点:卤代烃
题型:选择题

对无骨端外露的骨折伤员肢体固定时,要超过伤口上下关节。

题型:选择题

阅读短文,根据短文内容,从短文后的选项中选出能填入空白处的最佳选项。选项中有一项为多余选项。

     Long ago, people did not need money. They lived on wild animals, fruits and other plants.

     As time passed by, people learned to raise animals and crops. Sometimes, families produced more than they

needed, so they started to trade with other families. ____ However, it was not the kind of money we use today.

They used shells, rice, salt, large stones, etc.

     During the 600sBC, people began using coins as money. They soon found that coins were easier to carry

than goods and lasted a long time. _____

     The Chinese were the first to use the paper money, probably as early as the 11th century. The Italian

travelers Marco Polo saw the Chinese using money when he visited China in the 1200s. ____

     Today, we have many ways to pay for things. We do not use coins or paper money. Often people prefer to

pay for things by card.____

A. Later, countries began to make their own coins.

B. We use money to buy things every day.

C. Paying with a card is easier and safer than carrying around a lot of "real" money.

D. However, European countries did not start using paper money until 1600s.

E. Later, people began to use money as a means of exchange (交换).

题型:选择题

These are            .[ ]

A. man      

B. girl        

C. women

题型:选择题

正确的1P地址是______。

A.202.202.1

B.202.2.2.2.2

C.202.112.111.1

D.202.257.14.13

题型:选择题

涤纶长丝部分定向单股纱线

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