【单选题】基因工程的正确操作步骤是: ①将目的基因与运载体相结合,②将目的基因导入受体细胞, ③检测目的基因的表达是否符合特定性状要求,④提取目的基因 [ ]
【简答题】阅读短文,选择正确答案。 Did you see snow in your hometown last winter? Did you feel it was warmer than before? 'There have been 21 warm winters in China since 1986,' said scientists. They also said that in the p...
【单选题】下面文献属于哪一类? [1] 霍军 . 创新教育理念下体育教学方法理论与实践研究 [D]. 北京 : 北京体育大学 , 2012:15-17.
【判断题】母乳喂养经济、安全又方便,不易发生过敏反应。