'over the summer...' is right
...You could describe it as not just making or leaving tracks behind on mars, but in another way. As if you left tracks in everyones brains. (I don't know, at least I tried)
Answer:
from is the only prepositions there
Answer:
<em>In geometry, a coordinate system is a system that uses one or more numbers, or coordinates, to uniquely the position of the points or other geometric elements on a manifold such as Euclidean space.</em>
