along - an edge of paper. A route that won't nessesarily be affected by the mountains. The definition would be the most horizontal route. It might even go around the hills all the time avoiding any climbing. across - From one side to another. The complete route. over - actually going on top of the mountains. Train routes are usually made in a way to link up places of interest in the most efficient and direct route possible at the time. However if the mountains have a level plateau, then this could be possible. through - would suggest either it travells through the mountains by means of a valley in between or tunnels cut into the mountains.

Is this a trick question? :) They all sound right to me. The only different one to me is "along", which would imply that the tracks go along the length (or a part) of the Andes. I'm curious to see how else people understand this.

Craig has the right idea here. Without more knowledge it's almost impossible to say, although John's approach seems pretty logical too. The question really does not provide enough information to choose one answer as better than another (unless there is a reading associated with the question). Along would imply that the train stayed on one side of the Andes range, and travels for some distance that way. Across and over would imply that train went from one side of the range to another. Through is the most general, it could mean that it went through a tunnel from one side to another but it could also mean that it just meanders around the mountains from one place to another, could be to the other side but not necessarily. We can walk through the forest, which doesn't really say anything about where exactly we went, just that we went from one place to another through the forest. So, I would go with through, simply because it is the most general, and we have no other information (not without looking at a map) to tell us which is the best answer. Looking at a map, the journey starts very high on the western side of the mountains and travels south west along and through the range to Guayaquil in the plains. If the correct answer is along, it is probably because it actually does move parallel to the peaks of the range for about half the journey.

if we were walking or hiking we would say either over the mountain(s) or through the mountain(s) Thanks to google I Can tell everybody that the train from Riobamba to Guayaquil travels along a valley floor with mountains on either side and Guayaquil is on a lower level downhill from Riobamba, Riobamba is higher above sea level than Guayaquil. therefore the train goes through the Mountains before going gently down to Guayaquil. As the train nears Guayaquil it is in open country with no mountains on either side. it has to be D Through

C: over would be for a tourist train that is winched up a mountain or goes up a short steep incline but if the train goes through a valley or natural pass in the mountains or a pass made by cutting (tunnel etc) then you could say D through