I'm raising money for a good cause.

我正为慈善事业募捐。

His workmates made a collection for his leaving party.

事为告别晚会募捐。

We collected money in behalf of the homeless.

我们为那些无家可归人募捐。

We collected ￡478, but a very generous benefactor made it up to ￡500.

我们募捐了478英镑, 位非常慷慨捐款人凑足到500英镑。

I collect for Oxfam.

我为英国牛津饥荒救济委员会募捐。