When I returned to my hometown ten years later, I found it changed so much that I could hardly _____ it.

Don’t mention that at the beginning of the story, or it may _______ the shocking ending.

The rivers will become dirtier and dirtier________ we take action to protect them.

The teacher asked the students to do the experiment _____ small groups.

The thirteen stars on the flag _ the thirteen colonies that announced independence first.[ ]