2.1 The Compound Sentence Pattern

To join these ideas, we would use a comma after “purring” and use the coordinating conjunction “for” right after the comma.

To join these ideas, we would use a comma after “couch” and use the coordinating conjunction “and” right after the comma.

To join these ideas, we would use a comma after “sleep” and use the coordinating conjunction “so” right after the comma.

The comma should be placed before "was a happy day"

The comma should be placed after "every night"

The comma should be placed before "and"

No comma is needed.

I don't know.

to join the two sentences with a coordinating conjunction

to separate the two sentences without a coordinating conjunction

to show a cause-effect relationship

to show a contrasting relationship

to continue a negative thought

to join things or ideas that are alike or similar, implies a continuation of thought