One man in a uniform standing inside a school bus with the backdoor open , while another man sits on top of the boss wearing a similar uniform .
It is probable that a bus driver and his aide are picking passengers up for a field trip .
It is probably not the case that a bus driver and his aide are picking passengers up for a field trip .
It is probable that a bus driver and his aide are picking passengers up for a field trip .
A bus driver and his aide are picking passengers up for a field trip .