Jackie is taking her test, but Sam is dancing to disco music.

Brady loves Blake's devilled eggs, and Andrew does not.

Devin will not sing opera in front of the class, for she is shy.

Cullen is not afraid of heights, so Seth is.

The leaves were red and green.

The leaves were red, and some leaves were green.

We could have had chocolate, or we could have had cake.

We could have had chocolate, or cake with lots of sprinkles.

I wasn't sure about the answer, so I asked a teacher.

I wasn't sure about the answer, and asked the teacher.

I must be hungry, so I am writing about food.

I liked the weather this weekend, and the fall colors.

She could have had a new car, or a new truck.

The unicorns were alone, but not lonely.

The leprechauns danced, but the unicorns laughed at them.

Book talks are easy, and they are due on the 17th.

Some people prefer the book paper, not the book talk

Book talks are easy, but they must be done in the first ten minutes of lunch.

There are only thirteen days left to do a book talk, so you may want to spend time reading.

Some people prefer the book paper, but not the book talk.

Missing a subject in the second half

Missing a subject AND verb in the second half

Missing a comma

Missing a coordinating conjunction (FANBOYS)

I have studied Spanish for many years, my Spanish-speaking friends can chat easily with me now.

I have studied Spanish for many years; my Spanish-speaking friends can chat easily with me now.

I have studied Spanish for many years. So my Spanish-speaking friends can chat easily with me now.

She moved to Ireland; she preferred the tranquil setting; over America.

She moved to Ireland; she preferred the tranquil setting over America.

She moved to Ireland she preferred; the tranquil setting over America.

She moved to Ireland; and she preferred the tranquil setting over America.