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.

从10数到20，5个5个地数：10、15、____

某钾肥溶液的阴离子为NO₃^﹣、Cl^﹣、SO₄^2﹣、CO₃^2﹣、SO₄^2﹣中的一种或几种，现进行实验分析结果如下：

由此判断，此钾肥中一定含有____，可能含有____．