构造原理揭示的电子排布能级顺序，实质是各能级能量高低．若以E（nx）表示某能级的能量，以下各式中正确的是（　　）

①E（4s）＞E（3s）＞E（2s）＞E（1s）         

②E（3d）＞E（4s）＞E（3p）＞E（3s）

③E（5s）＞E（4f）＞E（4s）＞E（3d）         

④E（5s）＞E（4s）＞E（4f）＞E（3d）

①在实践中得到锻炼成长 

②获得一定的物质报酬

③增强服务社会的自觉性 

④拓宽视野，增长知识

阅读下面短文，掌握其大意，然后从各题所给的四个选项（A、B、C和D）中，选出最佳选项。

    Once when there was a famine (饥荒), a rich baker sent for twenty of the poorest children in the town, and said to them, “In this basket, there is a loaf (一条面包) for each of you. 1 it, and come back to me every2at this hour till better times come.”

    The hungry children 3 eagerly around the basket, and quarreled for the bread 4 each wished to have the largest loaf. At last they went away without even 5the good gentleman. But Gretchen, a poorly-dressed little girl, did not 6 or struggle with the rest, but remained 7 modestly in the distance. When the ill-behaved children had left, she took the 8 loaf, which alone was left in the basket, 9the gentleman's hand, and went home.

    The next day the children were as 10 as before, and poor, shy Gretchen received a loaf only nearly half the 11 of the one she got the first day. When she came home, her mother cut the 12 open, and then many new, shining pieces of silver fell out of it. Her mother was very much 13 , and said, “Take the money back to the good 14at once, for it must have got into the loaf 15 . Be quick, Gretchen! Be quick!”

    But when the little girl gave the rich man her mother's 16 , he said, “No, no, my child, it was no 17 . I had the silver pieces put into the smallest loaf to 18 you. Always be as contented (满足的), peaceable, and 19 as you now are. Go home now, and the 20 is your own.”