vi 是不及物动词, vt 是及物动词
英语中按动词后可否直接跟宾语,可把动词分成及物动词与不及物动词.
及物动词： 字典里词后标有vt. 的就是及物动词.及物动词后必须跟有动作的对象（即宾语）,并且可直接跟宾语.
如see 看见 (vt.) +宾语 I can see a boy.
其实所谓“及物”,就是后面可直接加宾语的动词,有被动形式,而不及物动词是没有被动式的,也不可直接加宾语,需加上介词.
及物动词后面可直接接宾语,不及物动词后面不可直接接宾语,一般要加介词后再接宾语.实际上很多动词既是及物动词,又是不及物动词.我举一个例子,就说write.如I am writing.和I am writing a letter.在前一个句子write是不及物动词,在后一个句子write是及物动词.又如,see是及物动词,但在特殊情况下如seeing is believing.
不及物动词就是一个动作不能施加到另一个物体上,也就是后面不能加宾语.
例如：He is running. run这个动词就是不及物动词,后面不能加sth.（不能说跑什么东西）
分清及物不及物动词:
分清动词的及物不及物是在英语学习中必须解决的首要问题.动词及物与不及物通常有以下几种情况：
a．主要用作及物动词.及物动词后面必须跟宾语.可以用于："主＋谓＋宾"；"主＋谓＋双宾"；"主＋谓＋宾＋宾补"结构.如：
He reached Paris the day before yesterday.
Please hand me the book over there.
They asked me to go fishing with them.
类似的还有：buy, catch, invent, found, like, observe, offer, prevent, promise, raise, find, forget, receive, regard, see, say, seat, supply, select, suppose, show, make, take, tell.
b．主要用作不及物的动词.不及物动词后面不跟宾语.只能用与："主＋谓"结构.
This is the room where I once lived.
类似的还有：agree, go, work, listen, look, come, die, belong, fall, exist, rise, arrive, sit, sail, hurry, fail, succeed.
c．既可以用作及物又可以用作不及物的动词,其意义不变.如begin 都是作"开始"讲.everybody , our game begins. let us begin our game. 类似的还有：start, answer, sing, close, consider, insist, read, learn, prepare, pay, hurt, improve.
d．既可以用作及物又可以用作不及物的动词,其意义完全不同.
这类动词作不及物动词是一个意义；而作及物动词时却是另一个意义.如lift作不及物动词时是指烟雾的"消散".we saw the mountain when the clouds lifted. 作及物动词时是"升高；举起".
He lifted his glass and drank.
类似的还有：beat vi.跳动 vt. 敲、打; grow vi.生长 vt. 种植
play vi.玩耍 vt. 打（牌、球）,演奏 smell vi.发出（气味） vt. 嗅
ring vi.（电话、铃）响vt.打电话 speak vi.讲话 vt. 说（语言）
hang vi. 悬挂 vt. 绞死 operate vi.动手术 vt. 操作
在英语错误中,“及物动词＋介词＋宾语”（transitive verb+preposition+object）,是常见的一种.所谓及物动词,就是谓语动词（predicative verb）,不必通过介词引荐宾语.相反的,不及物动词（intransitive verb）是不带宾语的.有许多动词,虽然性质是及物的,但不一定要有宾语,如下列的①a和②a便是这种情形：
①a. We study every day.
b. Do you study English every day.
②a. Please write clearly next time.
b. Can you write your composition now?
如果本质上就是不及物动词,就不会有宾语；若要宾语,就要借介词之助,一起连用才行,如③b和④b;③a和④a是错的；
*③a. The children are listening the music.
b. The children are listening to the music.
*④a. She is laughing the crippled man.
b. She is laughing at the crippled man.
反之,及物动词不必靠介词,就可以带宾语,如上述的①b和②b ,又如⑤和 ⑥：
⑤ John is giving a book to me.
⑥ Who will answer this question?
如果无意中把介词加上,就错了,如：
*⑦ Who will answer to this question?
下列这句从房地产广告中看到的句子,也犯了同样的错：
“We have many buyers awaiting for available units here.”
“Awaiting”是个及物动词,后面的介词“for”是多余的,要去掉；不然把“awaiting”改为“waiting for”也行.
许多人习惯上喜欢把介词加到及物动词后面,然后才带出宾语.最常见的是“emphasize/stress on/upon”和“discuss about”,如：
⑧ Singaporeans seem to have emphasized on material gains.
⑨ In our education system, we stress upon examination results.
⑩ World leaders spent a lot of time discussing about worsening economic problems.
显然的,这三句里的介词“on/upon”和“about”是多余的,不必要的.
下面是些类似的错误：
● The young must obey to their elders.
● Do not approach to that odd-looking man.
● The audience attacked on the rude speaker.
● Nothing can escape from his parents' eyes.
● Do you hope to serve for your nation?
● When did Susan marry with Paul?
介词“to, on, from, for, with”都要去掉才对.
为什么会有这些错误呢?主因是分不清楚及物动词和不及物动词的性质.其次,就是对同一个动词及其名词的句型有些混淆.解决之道有二.第一,要把“及物动词＋宾语”和“不及物动词＋介词＋宾语”划分清楚,如：
I did not answer him./ I did not reply to him.
He reached Londan yesterday./ He arrived in London yesterday.
第二,把及物动词转化为名词,然后加上适当的介词和宾语,如：
Don't approach such a person.
Is oral practice a good approach to language teaching?