新概念65课 为什么在set off后要加downhe set off down the main street of the city riding a baby elephant called ……在这个句子里,set off 是出发,那为什么要加down?

新概念65课 为什么在set off后要加downhe set off down the main street of the city riding a baby elephant called ……在这个句子里,set off 是出发,那为什么要加down? 新概念2第12课的三个set短语再加上set about分别表示什么意思(难点的b部分)并造句.分别是set out,set off,set up,set about造句 关于新概念二课文中某个语法的不理解新概念二中的65课有这么一句,He set off down the main street of the city riding a bay elephant called Jumbo.这个地方为什么用riding呢,是动名词还是现在分词,越详细越好, 谁知道新概念英语一册第53课为什么day,season,set,rise,night等要加s?为什么是单三呢? set out 与 set off 区别在哪? set out 与 set off 区别在哪? 在vfp中set safety off/on 在VF中,SET DELE OFF/ON set out,set up,set off,set set out,set up,set off,set the internet (was set up).set不是v吗,为什么在be后? 正则表达式：如何匹配指定单词后的第二个单词?比如,指定单词set.在如下字符串中：I have set this lamp on.Try to set it up.Don't set any ship off.我要匹配lamp,up,ship,该怎么匹配呢? 为什么不用被动 Panic set off across the whole country.set off是主动表被动吗？字典里有下面的句子：Panic on the stock market set off a wave of selling.在这个句子里set off就直接跟宾语了呀？ set off的过去式 set off啥意思? set off的意思 set off 是什么意思啊? set off什么意思?