下列叙述与化学知识相符合的是（   ）

中国古代的四大发明传入欧洲，加快了西方迈入近代社会的步伐 。“使推广民众教育成为可能”的发明是(　　)

心脏的四个腔中，心壁最厚的是（　　）

Martin: What do you want to be when you grow up, Jiamin?

Jiamin: I want to be a fireman (消防员). I think the fireman is cool.

Martin: And you, Lily?

Lily: I like children. I want to be a teacher. What about you, Martin?

Martin: My father is a police officer. He can stop bad people. So I want to be a police officer.

Jiamin: Police officer can help people. Your father is great, Martin.

Martin: Thanks. Look, Miss Wang is hard-working. I think the teacher is great, too.

我国未成年人保护法规定：不允许未成年人进入营业性舞厅、网吧等不适宜未成年人活动的场所。这一规定体现了对未成年人的 （ 　  ）