1. "You got that fountain the day after your husband disappeared. Now it starts to make some sense. In order to lay water pipe, someone would have to dig up the lawn, wouldn't they?"

2. Columbo (on phone): "Officer Corso?"
Corso: "Yes."
Columbo: "This is Lt. Columbo."
Corso: "Who?"
Columbo: "Lt. Columbo, we met this morning at the academy, remember?"
Corso: "Lieutenant, it's 3 o'clock in the morning."

3. "This is a fantastic rug. You know, we need a new rug and this one would be perfect. Fantastic piling. I bet you could lose a shoe in there for a week and you'd never find it."

OK, this one may be tricky, but not for the REAL fan!!

4. "Well, I was recenlty in an attorney's office nad he wasn't there, and his secretary was in the ladie's room. So I took that opportunity to search his waste basket. I was looking for a piece of gum. And I found it. I wanted to compare the bite marks in the piece of gum with the bite marks in a piece of cheese at the scene of the crime."

GOOD LUCK FRIENDS!!!!

Hi Fred!
I am sure I know #'s 1, 2 & 3, but as I always say, I won't be a quiz piggie, so I'll only answer one of them.
#3 is from Death Lends a Hand and Columbo says this to Brimmer about his shag rug at his beach house. It is where Brimmer is searching for the "missing" contact lens.
This is one of my all time favourite lines when Columbo says that he bets you could lose a shoe in there for a week!!

I'll take number 2--By Dawn's Early Light.

I'll hazard a guess at number 4 although I'm not entirely certain - was this said by Columbo in Columbo goes to College when he is talking to the Law students?

Yep, you've got it right :)

OK - is number 1 Requiem for a Falling Star? I reckon that makes sense. And I'm sure 2&4 are right but haven't a clue about 3 - will trust all of your superior Columbo knowledge!

Everyone beat me to it. You will just have to trust the fact that I already knew the answers to all four questions -- including the survival of the ploy to make the incorrect guess of "Agenda For Murder" for number 4.

David of course I believe that you knew all the answers! You always do!