1.Which one following sentence is puntuated correctly.

A.I saw many of my friends,that I had knew from high school.
B.Work was especially hard today,Ihad to train someone new to the job
C.I often carry a cellphone with me,it helps if someone is trying to reach me.
D.If I had arrived earlier,Iwould't have missed the opening act.

Make sure you let us know what YOU THINK; then someone here will be happy to comment and explain.

PS -- Don't forget to put a space after each comma.

I think it is D.

If I had arrived earlier,I would't have missed the poening act.
(It has two parts)

Yes, it's D.

The correct punctuated sentence is:

C. I often carry a cellphone with me, it helps if someone is trying to reach me.

To determine the correct answer, let's analyze the punctuation in each option:

A. "I saw many of my friends, that I had knew from high school."

In this option, a comma is used before "that," which is incorrect. When using "that" to introduce a restrictive clause, we do not need a comma before it. The correct version should be: "I saw many of my friends that I had known from high school."

B. "Work was especially hard today, Ihad to train someone new to the job."

In this option, there is a missing space between the comma and the following word "Ihad." The correct version should be: "Work was especially hard today, I had to train someone new to the job."

C. "I often carry a cellphone with me, it helps if someone is trying to reach me."

This option is correctly punctuated. It uses a comma to separate two independent clauses, providing a clear pause between the two thoughts.

D. "If I had arrived earlier, Iwould't have missed the opening act."

In this option, there is a missing space between the comma and the following word "Iwould't." The correct version should be: "If I had arrived earlier, I wouldn't have missed the opening act."

Therefore, the correct answer is option C: "I often carry a cellphone with me, it helps if someone is trying to reach me."