解释为驱逐时=dismiss
expel the trouble-making student 开除违纪学生
解释为排出时=emit
expel the smoke in the kitchen 厨房排烟
He could not expel from his mind the persuasion that he should see Marianne no more.
他无法从脑子里驱走这一想法：他再也见不到玛丽安了。
