----Daddy, can you buy me a new MP4 when you go to Beijing? ----You ______ get one if you are admitted to a key middle school. A. could B. shall C. may D. can 答案:B4.将经水培法长出一定数量根的洋葱(2n=16)低温处理一段时间后,用于观察根尖分生组织细胞的有丝分裂.下列有关叙述正确的是( )A.剪取的根尖不宜过长,以确保选取的全部是分生区细胞B.应用镊子尖弄碎根尖后再滴加龙胆紫,便于染色体着色C.低倍镜观察到物象后,即可直接转换高倍镜观察D.显微镜视野里,有可能观察到含有64条染色体的细胞