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.
A. Standing B. To stand C. Stood D. Stand
3、He made a mistake, but then he corrected the situation _____ it got worse.
A. until B. when C. before D. as
求解析,谢谢!