Потому что в вопросе, который начинается со слова WHEN всегда глагол ставится в Past Simple. В первом предложении действительный залог, значит вс глагол DID. Во втором предложении страдательный залог, значит вс глагол WERE (WAS)
Если в предложении есть сигнальные слова just, already, not yet, this week, this year, today, то глагол ставим в форму Present Perfect - have (has) + глагол в III форме.
НАПРИМЕР: When did he come? - Past Simple He has just come. - Present Perfect
1) my classroom is big 2)it is very light 3) after all classes it's always messy 4)windows in our classroom are white, walls are light-green, desks are light-brown 5) the blackboard Is dark-green, the floor is blue and the door is white, like windows 6) we have 5 windows in our classroom 7)we have no flowers on the windows, only on the floor, they stay in pots 8) the blackboard is in the front of the desks 9) we have near 11 pictures and photos on the walls and cabinets 10)out tv stay on the table near the blackboard 11)the clock hang from the top of the blackboard 12) we have one desk in our classroom: for teacher and for pupils 13)our classroom is very pretty and nice, I like to have lessons there
you are writing a letter
i am going to school now
she is going to clean the room
he is reading a book now