Diction and tongue twisters

First of all, last week's answer. I'm surprised no one said the really obvious answer. It was time to get a new watch. As for this week's...

Read each line aloud without making any mistakes. If you make a mistake you MUST start again without going any further. Try to complete it within 30 seconds.

This is this puzzle
This is is puzzle
This is how puzzle
This is to puzzle
This is keep puzzle
This is an puzzle
This is idiot puzzle
This is busy puzzle
This is for puzzle
This is forty puzzle
This is seconds! puzzle

Ok, hands up who did it.