Help in Game Maker (Gravity & object deletion)?

Question

I'm making a game similar to Mother load and I have a couple bugs.

First of all I've never used gravity in any of my games before so what's the direction for gravity to go straight down?

also How can I get it to delete an object under my main object? I tried delete other but it just deleted the object.

After I get the answers to these components I can finish the game.

Answer 1

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Answer 2

well with the gravity thing look at there site they have a tutorial which will get you up to speed as to the delete thing, try having the object switch with something else.