举例说明tell,told,said,say says的用法,

told 是tell的过去式；said 是say的过去式；says是say。
tell 与 say的区别：tell是告诉的意思，say是一般的说话：
a. She told me not to do it.
b. I told her I loved her.
c. She says she will not do it.
d. They say I'm very intellegent.

Do as i tell you 照我说的做
Do as i told you 照我说过的做
I say no 我说不
I said no 我说过了，不
The clock says half past two 时钟指向了两点半
Alan is waiter . he says may i help you every single day
Alan是个服务生，每天都要和顾客说我可以帮助你吗

told是tell的过去式,就是之前说的,有告诉的意思.
said是say的过去式,有说明的意思.
says是say的第三人称,比如：She says…是现在时