登记，是指行为人特定的旅游行为，在规定的时间内，向规定的主管机关办理登记手续，以表明其行为的______。
参考答案：合法性
β-内酰胺类抗生素的抗菌作用机制是（）
A.抑制二氢蝶酸合成酶
B.抑制细菌核酸代谢
C.触发细菌自溶酶活性
D.抑制胞壁黏肽合成酶
E.抑制细菌蛋白质合成
Not only ______ strict with us, but also ______ for us .
A．was the teacher ; did he care
B．was the teacher ; he cared
C．the teacher was ; did he care
D．the teacher was ; did he care
