２０-１９+１８-１７···+４-３+２-１用简便方法计算,

设总质量为m
m*20%/14 是氮的摩尔数
（m*20%/14）/2 是硫酸铵的摩尔数
（m*20%/14）/2*132 硫酸铵的质量
（m*20%/14）/2*132/m=94.28%

1、α粒子的散射现象；元素的放射现象 2、含有两个质子的氦原子荷 能穿过金箔的主要原因是相对于原子说占据的空间而言,原子核实在太小了

1.I ain’t doing my duty by that boy,and that’s the Lord’s truth,goodness knows.Spare the rod and spile the child,as the Good Book says.I’m a-laying up sin and suffering for us both,I know.He’s full of the Old Scratch,but laws-a-me!he’s my own dead sister’s boy,poor thing,and I ain’t got the heart to lash him,somehow.Every time I let him off,my conscience does hurt me so,and every time I hit him my old heart most breaks.
2.“Oh come,now,you don’t mean to let on that you like it?”
The brush continued to move.
“Like it?Well I don’t see why I oughtn’t to like it.Does a boy get a chance to whitewash a fence every day?”
That put the thing in a new light.Ben stopped nibbling his apple.Tom swept his brush daintily back and forth—stepped back to note the effect—added a touch here and there—criticized the effect again—Ben watching every move and getting more and more interested,more and more absorbed.Presently he said:
“Say,Tom,let me whitewash a little.”
3.Mr.Walters fell to “showing off,” with all sorts of official bustlings and activities....The librarian “showed off”—running hither and thither with his arms full of books....The young lady teachers “showed off”....The young gentlemen teachers “showed off”....The little girls “showed off” in various ways,and the little boys “showed off” with such diligence that the air was thick with paper wads and the murmur of scufflings.And above it all the great man sat and beamed a majestic judicial smile upon all the house,and warmed himself in the sun of his own grandeur—for he was “showing off,” too.
4.Tom was a glittering hero once more—the pet of the old,the envy of the young.His name even went into immortal print,for the village paper magnified him.There were some that believed he would be President,yet,if he escaped hanging.
5.Huck Finn’s wealth and the fact that he was now under the Widow Douglas’s protection introduced him into society—no,dragged him into it,hurled him into it—and his sufferings were almost more than he could bear.The widow’s servants kept him clean and neat,combed and brushed….He had to eat with knife and fork; he had to use napkin,cup,and plate; he had to learn his book,he had to go to church; he had to talk so properly that speech was become insipid in his mouth; whithersoever he turned,the bars and shackles of civilization shut him in and bound him hand and foot.

1)c20/9 * 3/4 = 10/64/3 * 9/7 = 12/77/9 * 9/4 = 14/84/9 * 4/1 = 16/91/4 * = 18/10 =5/36分子为：10,12,14,16,18分母为：6,7,8,9,102)C5*3+2=175*4+1=215*5+0=255*6+1=315*7+2=37

460千米

不知道啊啊啊阿嗄克当量

不知道你有没有房地产估价理论与方法这本书,在P379里有关于补地价的测算.对于改变土地使用权出让合同约定的土地用途、容积率等土地使用条件的,补地价的数额在理论上为批准变更时新旧土地使用条件下的土地市场价格之差额,即补地价等于新土地使用条件下的土地市场价格—旧土地使用条件下的土地市场价格.在题目中,新条件为商业,剩余60年,但法定最高年限为40年,所以价格为150元*K40＝135.42,旧使用条件为住宅,当时取得时价格为80元,在补交地价时剩余年限为60年,所以价格为80*K60＝77.57,之差为57.84,和答案不一样,选了个最接近的咦,刚才我怎么没看到啊,所以又发了一遍,可不是故意的呀.查看原帖

80/(80+20)=0.8=80%

一杯盐水的含盐率为20/100,盐占水的百分之25