Use of "too"

[Tom]

Hello everbody

I am a bit confused

Have you ever noticed that sometimes too comes at the end of a sentence following a comma and sometimes not.(Examples are following)? Is it optional?

1- A lot of time is needed , too.
2- He was killed too.

Why comma in the first and why not in the second?Please help me understand it thoroughly.

Ever yours

Tom

[Mister Micawber]

.
Some think it is required and others do not (especially in short statements). To be careful, use the comma in essays and tests.
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Native English teacher at Mister Micawber's