G5 U2 W1 pg 13

When a sentence begins with an introductory phrase, the phrase should be set

off from the rest of the sentence with a comma. The introductory phrase is

“extra.” If you remove it from the sentence, the sentence still makes sense.

At the end of the first chapter, the astronauts see a strange light.

Rewrite each sentence using a comma to set off the introductory phrase