Tom was only seven years old. He likes watching ____ very much. He ____ went to the movies before. One day, he ____ to have a try. When getting to the cinema, he bought a ticket (票) and went in. ____ after two or three minutes, he came out, and bought the second ticket and went in. After a few minutes, he came out again and bought the third ticket. 

    Then a girl ____ about him and asked, “Why do you buy so many tickets? How many friends do you meet?” “No, I have no friends here, but a woman always stops me at the door and tears (撕) my ticket.”

All the parents ____ ____ their children's ____.

下列各项中，属于人体第一道防线的是（）

①胃液对病菌的杀灭作用  

②唾液中溶菌酶对病原体的分解作用

③呼吸道纤毛对病菌的外排作用 

④皮肤的阻挡作用

⑤效应T细胞与靶细胞接触 

⑥抗毒素与细菌外毒素结合．