Caren,
Please help Choose the correct answer:
Help (yourself - yourselves) everyone. There (is - are) plenty more.
Let us imagine that we are at a party with lots of other people. We hear the announcement.
Help (yourself - yourselves) everyone.
In my opinion, we could regard �the group of guests � at the party as an assembly, a company, one indivisible gathering.
We regard the group as having singular existence.
We DO NOT think of the group as individual persons.
Then, we would use �yourself �.
Alternatively, we could regard the �group of guests � at the party as a collection of several, separate, different individuals.
We regard the group as having plural existence.
We DO think of the group as individual persons.
Then, we would use �yourselves �.
There (is - are) plenty more.
If the article/articles referred to CAN NOT be counted ... "1, 2, 3," etc. ... then the reference is to something UNCOUNTABLE, such as �wine �, or �food �, etc.
We use:
"There is plenty more".
If the article/articles referred to CAN be counted ... "1, 2, 3," etc. ... then the reference is to something COUNTABLE, such as �sandwiches �, or �bottles of juice �, etc.
We use:
"There are plenty more".
Without any further information than what is given, I would choose:
"Help yourselves, everyone! There is plenty more!"
I am being polite and speaking to the guests personally, as individuals. I am indicating that there is plenty more food/more drink available.
Please Note: This is my opinion.
Others may disagree.
But, I hope that I have helped you.
Les Douglas