下面是小旋同学测菜油密度的实验步骤，其中合理的顺序是（　　）

①把适量的菜油倒入烧杯中测总质量m₂；

②用天平测出烧杯和剩余菜油的质量m₁；

③把天平放在水平台上，游码移动零刻度线处，调节平衡螺母，使天平横梁平衡；

④把由ρ=$\frac{m}{v}$计算出菜油的密度；

⑤一部分菜油倒入量筒中读出菜油的体积V．

下列属于对自己青春负责的表现是（   ）
①与人相约，守时守诺                   ②对待学习，发奋图强
③犯下过错，不找推脱                   ④对待生活，讲求享乐

古人云：“流水之声可以养耳，青禾绿草可以养目，观书绎理可以养心，弹琴学字可以养脑。”这充分说明休闲的功效有（    ）

①找到适合自己的休闲方式                            ②能获得精神上的慰籍，放松紧张的心情

③能解除体力上的疲劳，恢复生理的平衡     ④会带来学习进步，但会使视力下降

阅读理解

    This happened about one thousand and seven hundred years ago．One day somebody sent Cao Cao, the king of Wei an elephant．Cao Cao wanted to know its weight(重量)．“Who can think of a way to weigh it?”he asked．But nobody knew what to do because there was nothing big enough to weigh it．

    Then Cao Chong, one of the king's young sons, came up and said, “Father, I've got an idea．Let me have a big boat and a lot of heavy stones, and l'll be able to find out the weight of the elephant．''

    Cao Cao was surprised, but he told his men to do as the boy asked．When the boat was ready, the boy told a man to lead the elephant down into it．The elephant was very heavy, and the water came up very high along the boat's side．Cao Chong made a mark along the water line．

    After that the man drove the elephant onto the bank．Cao Chong then told the men to put heavy stones into the boat until the water again came up to the line．

    Cao Chong then told the men to take the stones off the boat and weigh them one by one．He wrote down the weight of each stone and then added up all the weights．In this way he got the weight of the elephant．