Commas in Compound Sentences

Front

It rained all day, _______ we didn't go outside.

Back

so

Front

Simon wants to buy a new cell phone, ________ he doesn't have enough money.

Back

but

Front

In a compound sentence, the comma comes ______________ the coordinating conjunction.

Back

before

Front

Does this sentence need a comma?
I wanted to go to the store but I decided to stay home instead.

Back

Yes 

Front

What is the correct way to combine the following two simple sentences into a compound sentence?

Snorlax swam the English Channel. He was very tired.

Back

Snorlax swam the English Channel, so he was very tired.

Front

What is the correct way to combine the following two simple sentences into a compound sentence?

Wishbone wanted to take a nap. He was too busy reading.

Back

Wishbone wanted to take a nap, but he was too busy reading.

Front

Complete the sentence with the coordinating conjunction that makes sense: You may have soup, ____ you may have salad. Options: or, and, nor, yet.

Back

or