Can someone please explain why:

1) 3 E {1,2,3}

2) 1 is not a subset of {1}

3){2} is not a subset of {1,{2},{3}}

4){1} is a subset of of {1,{2}}

I kind of understand the basics but am still lost when it comes to knowing how to read these in my head and understand what going on....

Thanks