There are many expressions commonly used in English with the comparison form ‘as … as’.
There is no magic rule to help you remember them. You just have to learn them. Sorry!
Take a look at the examples below.
As good as done.
If something is as good as done it means it is virtually (or almost, or nearly) finished or accomplished.
E.g. The presentation for tomorrow is as good as done. Just give us a few more minutes to complete it.
As mad as a hatter.
If someone is as mad as a hatter it means they are mentally deranged, crazy or insane.
E.g. She’s as mad as a hatter. She says some of the strangest things I’ve ever heard!
As pleased as Punch.
If someone is as pleased as Punch they are very happy or delighted about something.
E.g. My boss was as pleased as Punch when he heard we had won the pitch and gained a new client.
(This phrase refers to the character of Mr. Punch in the British puppet play Punch and Judy.)
Have fun learning English!
Louise