Two main techniques have been used for training elephants,
驯象有两种主要的方法，
新概念英语第四册
Lesson 41 Training elephants
📚 句中词汇解析
从本句中提取的重要词汇
adj. 主要的，最重要的;全力的;
n. 最主要的部分，重点;主要管道;体力;[航海]公海;
💡 妈妈(ma)在家里(in)是 主要的成员
"All the students were asked to assemble in the main hall."
全体学生获通知到大礼堂集合。
近义：head, intrinsic, leading, major, master, material
反义：associate, attache, parallel, auxiliary, accessorial, accessory
adj. 用过的;习惯于;二手的;旧的;
v. 使用（ use的过去式和过去分词）;常常，经常;
"Things ain't what they used to be."
现在情况不比从前了。
近义：outworn, worn, utilized, wonted, accustomed
反义：unused, unworn
n. 训练;培养;（枪炮，摄影机等的）瞄准;整枝法;
v. 训练，培养( train的现在分词);教育;瞄准;整枝;
"training for non-professional staff"
对非专业员工的培训
近义：learning, preparation, taming, capacitation, coaching, habilitation