锅炉采用二级点火系统，燃烧设备装有四角三层（）支供暖炉用的蒸汽雾化平行管式可伸缩油枪

氨气是一种重要的化工原料．完成下列填空：

（1）写出工业合成氨的化学方程式．______

（2）如图所示，将集有氨气的试管倒置于水槽中，观察到的现象是______．

（3）NH₄HCO₃是常用的氮肥，在施用时若受热会释放出______而降低肥效．检验NH₄⁺的方法是______．

David stayed inside himself, ______ to be alone, or in a corner of the cabin.

A．to want

B．wanted

C．being wanted

D．wanting

Money Matters

Parents should help their children understand money. 71 so you may start tallking about money when your child shows an interest in buying things,candy or toys,for example.

1.  The basic function of money

Being explaining the basic function of money by showing how people trade money for goods or services.it’s important to show your child how money is traded for the thing he wants to have.If he wants to have a toy, give him the money and let him hand the money to the cashier .72 when your child grows a bit older and understands the basic function of money, you can start explaining more complex ways of using money.

2.Money lessons

Approach money lessons with openness and honesty.    73  If you must say no to a child’s request to spend money,explain,”You have enough toy trucks for now.”Or,if the request is for many different things, say.“You have to make a choice between this toy and that toy.”

3.    74 

Begin at the grocery store. Pick put similar brands of a product—a name brand butter and a generic(无商标产品),for example.You can show your child how to make choices between different brands of a product so that you can save money.  75  If he chooses the cheaper brand, allow him to make another purchase with the money saved.Later,you may explains how the more expensive choice leaves less money for other purchases.

A．wise decision.

B．The value of money.

C．Permit the child why he can—or cannot—have certain things.

D．Talk yourself what things that cost money are most important to you.E. Ask yourself what things that cost money are most important to you.

F. Talk about how the money bought the thing after you leave the toy store.

G. The best time to teach a child anything about money is when he shows an interest.

—  Was it by cutting down staff _    _she saved the firm?   

—  No, it was by improving work efficiency. [ ]

A. when        

B. what      

C. how          

D. that

Dean氟牙症分类可疑（）

A.釉质上的白色程度浅，有时呈云雾状

B.釉质上的白色程度较明显，呈纸白色

C.釉质上的白色不透明区范围更加扩大，但覆盖面积不超过牙面的50%

D.釉质表面大部分受累而变色，常有细小的凹坑状缺损，多见于唇颊面

E.釉质表面全部受损，凹坑状缺损明显，牙冠失去正常外形且脆性增加，对美观和功能都有严重影响