中英成语俚语800对184：害群之马
害群之马
one scabbed (sickly) sheep infects a whole flock.
the rotten apple injures its neighbour.
bad egg of the community.
eg：that naughty boy is the black sheep of the family.
中英俚语俗语来源：庄子：“夫为天下者，亦莫以异乎牧马者哉?亦去其害马者而已矣。”