It was nearly mid-night ________ Henry began to feel terrible．
A.untilB.thatC.whenD.while在线课程C
until前面应该用表示动作的延续动词；that和it构成强调句式时mid-night前应该加介词at; while在引导时间状语从句时其谓语动词用延续性动词，故C为最佳答案。在此when相当于at that time。句意为：午夜时，亨利突然感到不舒服。