携带编码毒素的基因使无毒的白喉棒状杆菌产生白喉毒素 A.接合 B.转化 C.转导 D 发布时间:2017-07-20 12:37 │ 来源:www.tikuol.com 题型:单项选择题 问题: 携带编码毒素的基因使无毒的白喉棒状杆菌产生白喉毒素A.接合B.转化C.转导D.溶原性转换E.原生质体融合
题型:单项选择题 The old couple walked rather slowly, and could be seen, from time to time, to stop and rest, ________ out to sea.A.to be staringB.staredC.having staredD.staring 查看答案