_______ for a long time, most of the crops in this area died from lacking water.
D
Therebeingnorain为therebe句型的独立主格形式。
Evenwiththenewdevelopmentinresearch,onlyatiny________ofalltestsaredonewithoutusinganimals.
I’vegottheorderfromthebossthatthework_______finishedbefore5p.m.today.
Itisdifficulttounderstandthiskindof_______calculation.