irregular verbs

Dear colleague,
i'm an english teacher from Belgrade and I just wanted to ask whether
forms of irregular verb To cost -cost ad costed are both correct.

thanks in advance

[Tdol]

They are different- the form 'cost' describes how much you paid for something. 'Costed' is used for giving estimates- the builder costed the job at five hundred pounds.

[Casiopea]

Originally Posted by catryn

Dear colleague,
I'm an English teacher from Belgrade and I just wanted to ask whether forms of the irregular verb To cost -cost and costed are both correct. Thanks in advance.

In addition to what tdol said,

the verb to cost has the following forms: cost, cost, cost

Present: cost(s)
Past: cost
Participle: cost

Present
The book costs $4.
The books cost $4.

Past
The book cost $4.
The books cost $4.

Participle
The book had cost $4.

:D