The virulence of both mutants, as represented by median lethal dose (LD50), was not significantly different from that of the parental strain.是什么意思_The virulence of both mutants, as represented by median lethal dose (LD50), was not significantly different from that of the parental strain.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句