When combining two complete sentences with a conjunction ("and," "but," "or," "for," or "yet"), precede the conjunction with a comma. Example: Still, the sun is slowly getting brighter and hotter, and ...

Here are two sentences: Lilly ate an ice cream. She read a book. Using a conjunction they can be joined to make one sentence, like this: Lilly ate an ice cream and read a book. Write the sentences ...