________ it was very late, ________ he was still doing some experiments in the lab．
A.Although; butB.Although; yetC.Even though; butD.Though; but在线课程B
although/though可以和still、yet连用，但不可以和but连用，所以选择B．本句是一个让步状语从句，而且带有副词．句子的意思是“尽管已经很晚了，他依旧在实验室做实验”．