时期是人生学习和发展的宝贵阶段。
青少年
—I worry about ______ enough time and energy to finish that job.
—Don’t worry about it. I’ll help you!
A.not having
B.not have
C.didn’t have
D.don’t have
一级动力学的特点在于()
A.一级速率常数不随体内药物浓度的变化而改变
B.不同剂量的给药具有相同的半衰期
C.属于被动转运
D.属于主动转运
E.一级速率常数随体内药物浓度的变化而改变