用交流电绕制电磁铁如何确定磁极

What were you doing then?(then 可换成at that time吗?）它们能互换吗? I have not any brothers and sisters 的同义句 如:生死 这样的词语有哪些? A:Hi,Tom,are you free now?B:Yes,__________ Mary. __Are you free you new?__Yes,I__________.(be) are you free now?A yes i do B no i can't C sure Mr Lin always make his class __ and keeps his students __ in class.alive和lively 有什么区别?为什么选那个答案?Mr Lin always make his class __ and keeps his students __ in class.A:alive,interesting B:alive,interested C:lively,interesting 人生在世的意义所在,以及存在的价值是什么 人生在世,为的是什么,健康.快乐.财富.名誉 Mike does not have any brothers(同义句)Mike( ) ( ) any brothers （每格一词） 人生在世,活着到底是为了什么?存在的价值又在哪里体现?平凡或者出色,积极或者消极,到头来都是一个终点,那活着的意义又在哪里? It's your ____ (顺序）to sing a song. Is it your turn____the song?(sing)用所给单词的正确形式填空 l am going to visit (kunming)就括号里提问 i was born to sing your song 歌词 A friend is someone knows the song in your heart and can sing it back to you when you have forotten是什么意思? still、all the time 翻译? After knew you fourth time keeps the tear翻译成中文 为何清军打不过八国联军,却能打败太平天国?太平天国有军队几十万,打了十几年,也没推翻满清,反而被灭.而英法联军、八国联军,人数那么少,只有一两万人,却能几十天就攻陷北京,逼清帝逃跑 关于八国联军的历史问题八国联军侵华前,据清政府统计,天主教、基督教、东正教在华的外籍传教士已有3200多人,入教的中国人达80余万人,教堂遍布全国城乡.（1）从政治和社会方面简单分析 to (cause to) arrive at a place after moving down through the air什么意思 as a super fans of kobe.we had learned we should always keep moving!seize the day and place no trust in tomorrow! 谁知道 对联 张之洞 的上联是什么 张之洞看不起梁启超吗﹖ 英语翻译我们本来可以按时完成那本书的. 英语翻译1·要是我有翅膀,我就飞到到美国去2·即使明天太阳从西边出来,我也不会那么做3·我到宁愿他明天给我打电话4·他建议这个会议不应该被推迟5·如果你没帮助那个孩子将会发生什么 阅读短文,判断对错.(补充两题) 4.wind is moving air.5.we can阅读短文,判断对错.(补充两题)4.wind is moving air.5.we can neither see nor feel air. and the wind is moving slowly.的翻译 The wind is b____ hard but the air is cleThe wind is b____ hard but the air is clean. 张之洞与洋务运动的故事 张之洞是谁? 简介张之洞.顺便说一下平远号是谁造的（战舰,甲午海战中一炮击中日旗舰“松岛号”水雷室的“平远号”）