More to explore:
Two, too, & to in English
Every English teacher needs a poster of this.
BBC Learning English - Talking Business
Learn English in New York! TOEFL Class! TOEIC Prep! Business English! Happy English!
English at Work - a series by the BBC focusing on English communication in the office
Grammar: Commonly Misused Words. Great for non-native English speakers like me.
This is an introductory lesson/activity/worksheet that deals with twenty common and useful English proverbs. Free