高一物理寒假作业

人们往往是根据什么对生物进行分类? 一根圆柱形管,把它截成两段圆钢管后表面积比原来增加了12平方厘米,这根圆柱管原来的体积是多少?一米长的圆柱管，把它截成两段圆钢管后表面积比原来增加了12平方厘米，这根圆柱管原来 节日用的小彩灯是串联还是并联?请说明原理. 街上的路灯一般是并联,开关与它控制的用电器是__ 节日彩灯是串联还是并联? 节日里所用一串小彩灯,各个灯是__连在电路中的,开关控制__灯,电流依次流经__小彩灯；家里的照明灯家里的照明灯、电视机、电风扇、空调等家用电器是__联在电路中的,电路中的电流分为__, 三节电池串联,三盏点灯并联,开关控制三盏电灯 某种铁矿石样品的主要成分是氧化铁,经分析确定含铁元素为百分之四十二,求样品中含氧化铁的质量分数 五氧化二磷有毒吗?有多大毒性? 五氧化二磷是否有毒 五氧化二磷有没有毒 明矾有毒吗 一个长方体,长和宽尺寸不变,高减少2厘米后就变成一个正方体,这样长方体的表面积就减少48平方厘米,原来这个长方体的长、宽、高各是多少? 一个正方体的表面积是24平方厘米,把它切成两个同样大小的长方体,这个长方体的表面积是（ ）平方厘米,体是多少（ ）立方厘米.要列式,要说原因. 1.现有1000t含Fe2O3的铁矿石,问可以炼多少吨纯铁?2.已知化合物HnRO2n-1(2n-1为右下角角标)相对分子质量为M.求(1)R化合价 (2)R相对原子质量?（3）原子团RO2n-1(2n-1为右下角角标)化合价?3.4.6g某物质在 70吨含氧化铁60‰的铁矿石中含铁元素多少吨? 很多美国人用英语说有复数吗? i hope to buy some presents for my family and friends 不是说hope+sb+todo不能修饰人吗? she went to buy some tickets for boating for her classmates.为何不用to sb.而用for sb. 一根圆柱形钢管截成4段,表面积增加了75.36平方厘米,这根钢管的底面半径是多少厘米?怎么半径不是3厘米啊 底面半径是4厘米,高是6厘米,求表面积 长21宽14的缸 需要多大功率的过滤器?3W的够用么? 一个圆柱,表面积是345.4平方厘米,底半径是5厘米,求它的高. 50的小缸到底用什么样的过滤器好点呢,现在有个挂式过滤但是效果不好,还有加热棒用多大的,主要过滤水中杂物,急 如何除去铁矿石中的SiO2 如何将bought,friends,pesents,for,my,during,I,the,hoildays,some连词成句? 连词成句bought my l for presents friends 连词成句,1.bought,griends,presents,for,my,during,l,the,holidays,some2.better,is,year,arunner,than,Danny,this,year,last,3.of,is,school,the,Wendy,our,best,jumper,in,one,4.fun,Sports,do,and,let's,have,in,best,Day,our, A great man once said it is necessary to dill as much as possible,andthe more you apply it in real dill 充当什么成分? Once an old man went to see a doctor.The doctor looked him over carefully and said,“Medicine won怎么写 Once an old man went to see a doctor.The doctor looked him over carefully and said,““Medicine won’t help you.You must have a good rest.Go to bed early,drink milk,walk a lot and smoke one cigar a day.Go to the country place for a mouth.”After a man once said how useless it was to put advertise 阅读理解A man once said how useless it was to put advertisements in the newspapers."Last week,"he said,"my umbrella was stolen from a London church.As it was a present,I spent twice its worth in