only to pass or turn left
There is no "fast" lane - all lanes are bound by the speed limit of that road. Basic rules of the road dictate that slow traffic keep to the right, and that the lefthand lanes be used for passing (this is in countries which drive on the right - in countries which drive on the left, it would be the opposite).
. . . . in the right lane unless passing another vehicle.
When approaching a curve to the right on a narrow road you should make sure you slow down to keep your tires on your side of the road. Oncoming traffic will need to maintain tight control to navigate the curve and will fight drifting into the opposite lane on the curve.
The right one (Slow Lane)... The left is for Passing
If there are no cars coming on the opposite lane, slow down A BIT and drive along the very side of the road so the other car can easily drive past you. You don't actually have to do this, but it's polite.
some states it is against the law to drive in the left lane UNLESS you are passing. This is do to emergency vehicles using the left lane and being blocked by people not paying attention. You can get a ticket for driving in the left lane in some states. No , most cops dont give them, BUT if you impeed the passing of an ambulance do to it, and there is a cop around, look out.
Then you slow down and drive with caution.
I am not sure on why some people drive slow on the road. I have seen that old people and people that are lost usually drive slower than normal.
I would first honk my horn to try to get their attention, and slow down as much as possible. If there is no avoiding the oncoming car i would drive off the road and aim for something soft to hit like bushes.
Trucks/Lorries, or any slow moving vehicle.
Very Very Slow,trying to be extra careful.ORYou Don't Drive at all.
In general you should drive in the right lane and use the left lane only to pass when necessary. (On some stretches of I-20 and I-35 you'll see this posted.) If traffic is heavy, you should stay in the lane that's going the speed you want to drive; usually this is slower in the right lane and faster in the left lane. If by "four lane road" you mean four lanes in each direction, that's personal preference -- I leave the far left to the speed demons, the far right to people getting on and off, and second from the right to the tractor-trailers; my preference is second from the left. The goal is to allow traffic to flow smoothly. Going too slow in the "fast" lane causes traffic to back up (and get mad at you), and rapid lane changes can cause accidents. Pick a lane and stick to it, and go the same speed as those around you -- if everyone did this, we'd all get there on time.