The fireman succeeded in saving all the people in the house on fire, they knew they were in great danger themselves.
A. because
B. since
C. unless
D. though
网友回答
A. because
B. since
C. unless
(答案→)D. though
解析：A. because因为（引导原因状语从句）， B. since自从（引导时间状语从句），C. unless除非（引导条件状语从句），D. though虽然（引导让步状语从句），句意：消防队员成功的在着火的房间救了所有的人，即使他们知道他们自己很危险。根据句意选D。