Green Glass Door

Does anybody know how to play green glass door? Some things are behind the green glass door, and others are not. I will give a few examples and you try to figure out the pattern. Do not, under any circumstances, say what the pattern is!! Instead try and give an example of things that are behind the door things that are not. I will tell you if it follows the pattern or not. If you figure out the pattern, just do what I do (tell people if they're right or wrong, and post the occasional example.)

Behind the door...

there is a moon but no sun.

books without pages.

trees but not bushes.

a street but no road.

can an apple go through but not an orange?

Behind the door you may attend classes at school or college but not courses at a university.

you're both right

i know ;D

you will find green but not blue.

so easy.

except maybe certain shades of blue... dunno.

Behind the curtain you find grass seeds but no soil

cows say "moo" but pigs dont say "oink"

the moon shines but there is no sun

some are cool, but no one is awesome.

what else is there.... cuckoos not pigeons

doors not windows....

everyone is good, and no one is bad

gimmewuchagot is clearly onto it. Hes got the name and everything.

behind the door people have heels and feet but no toes or ankles

BTW, thanks

Behind the door there is sleet but no snow

i think you can find cheese but not pie

You guys are way to smart...

no it's just really easy to see in writing

when talking it'd be a lot harder