[Q]: [Thesetwosmallgroupsoftravellerswerethevanguardofpartiesoflightandofdarknesswhich,likeamanandhisshadow,havegoneeversincethroughthecenturies,andeverwestward.]
[A]: [These two small groups of travellers were the vanguard of parties of light and of darkness which, like a man and his shadow, have gone ever since through the centuries, and ever westward.]
[Q]: [-Heightalert,heightdifferencemeasuring,climb/descent,verticalspeed]
[A]: [- Height alert, height difference measuring, climb/descent, vertical speed]
[Q]: [TheArctic-TheArcticIsanEcosystem:TheArcticGradients]
[A]:
[The Arctic - The Arctic Is an Ecosystem: The Arctic Gradients]