The following people will on duty today.

The following people will be on duty today.

The following people will on duty today.
错了
The following people will be on duty today.
原句无谓语 不算句子

The following people will be on duty today.
on是一个介词，在will后on前必须加助动词be

至少是

will be

吧

以下人员今天值班。