题目选项分析

Discussion of greenhouse effects has usually focused on whether Earth would grow warmer and to what extent,, but climatologists have indicated all along that precipitation, storminess, and temperature extremes are likely to have the greatest impact on people.

Discussion of greenhouse effects have usually had as a focus the possibility of Earth growing warmer and to what extent it might,, but climatologists have indicated all along that precipitation, storminess, and temperature extremes are likely to have the greatest impact on people.