In individual activities we could accomplish with a single one, because we cannot have any vehicle in every branch of we need others to come help us on what we could do.
In each activity, we can not accomplish alone, because we alone can not place a substance in each branch, we need people to help us in what we can not do.
In each activity, we cannot do it alone, because we cannot have any branches only ability we need to get someone else to help us in what we can't do it.