8.Experts believe that the process of " desertification" could encompass half the continent should current patterns of land use be allowed that they will continue.
B. should current patterns of land use be allowed to continue
D. if there is the allowing of current land-use patterns to continue
我記得老莫有說過Should是假設的用法 代替 if
不知道版上有誰有關於這個的解釋
並且分析一下 為什麼選B不選D
謝謝!