277- The author points out that most true avalanches --------. A) are considered to be falling rock not of snow or ice
B) happen when the snow has started to melt
C) take place when the snow has melted a little and then frozen hard again
D) rarely leave behind them a bare rock surface
E) cause considerable disintegration of the rock surfaces they come in contact with
278- We can infer from the passage that during an avalanche -------- A) rock fragments are likely to be carried down with the falling snow
B) the falling snow and ice start to melt very soon
C) there is an absolute threat of life
D) the failing snow is immediately followed by excessive rain
E) failing snow banks up steeply against the nearest rock face
