1、Only after we left the building ______ how dangerous the s

1、Only after we left the building ______ how dangerous the situation had been.
A.was I realized B.I realized C.did I realize D.I was realized
2、______ on the top of the tower,and you can see the whole city.x05
A.Standing B.To stand C.Stood D.Stand
3、He made a mistake,but then he corrected the situation _____ it got worse.x05
A.until B.when C.before D.as