Correct the punctuation by inserting periods, commas, and apostrophes where and if appropriate.

1. We tested his hearing with whistles bells and horns.

Answer:

We tested his hearing with whistles, bells, and horns.

2. The serial 7's revealed in my opinion evidence of abnormalities

Answer:
The serial 7s revealed in my opinion, evidence of abnormalities.
* If you use capital letters or numbers, you do not need to use apostrophes.
not 100% sure where the comma should go

1 is correct.

2 would be better written like this: In my opinion, the serial 7s revealed evidence of abnormalities.

If you have to keep #2 pretty much as is, though, then put commas before and after "in my opinion."

That is , in my opinion depressing

The serial 7's revealed, in my opinion, evidence of abnormalities.

3. Its time to start preparing for the party

Answer:

It's time to start preparing for the party.

4. We have a total of twenty-seven participants

Answer:

We have a total of twenty-seven participants.

5. He decided to take a vacation and visit his family to mexico

Answer:

He decided to take a vacation and visit his family in Mexico.

6. Sarahs dog is always barking at the mailman

Answer:

Sarah's dog is always barking at the mailman.

The serial 7s revealed, in my opinion, evidence of abnormalities.

3. Shes angry because Ive been late before.

Answer:

She's angry because I've been late before.

4. Please read pages twenty two through thirty four.

Answer:

Please read pages twenty-two through thirty-four.

5. He was absent to day.

Answer:

He was absent today.