A:实验中要控制胰蛋白酶溶液浓度和处理时间,以免损伤细胞
B:培养液中应适当加入青霉素、链霉素,以避免杂菌污染
C:曲线bc段产生的主要原因是培养液中营养物质不足及有害代谢产物积累等
D:培养第6天时,新产生的细胞数等于死亡细胞数
This is a s____ of twin brothers, Justin and Paul. Their friend Susan calls them for h____ . Justin and Paul drive to Hill Building q____ . Three man in police uniform p____ them into a green van. They are not p____ . They are the robbers. The twin brothers aren’t a____. Paul opens the back door of the van w____ a knife. They take different r____ to the police station. They meet the robbers a ____ in the police station. They are s____ . The policemen stop the van because the back door of the van is open.
一位在浙江求学的黑龙江学生,在生活中有以下感受,其中与事实相符
作文:
在人生的长河中,我们时时刻刻在书写着。书写一段美丽的友情,幸福永远;书写一场激烈的球赛,快乐常在;书写一段精彩的青春,豪情万千……
请你以“书写 ”为题,写一篇文章。
要求:①在横线处填上合适的词语,将题目补充完整;②文体不限(除诗歌外);③不少于600字;④文中不得出现真实的人名、校名、地名。