1.No one could leave the stadiumuntil 2.30.

=>It was not until......2.30 that someone could leave the stadium............

=>Not until......2.30 could someone leave the stadium ..........

2.She were not allowed to open her presents until her birthday.

=>It was not until.......her birthday that she was allowed to opne her presents .......

=>Not until............her birthday was she allowed to opne her presents ........................

3.We did not have any holiday until last summer.

=>It was not until.......last summer that we had some holiday .......

=>Not until........last summer did we have some holiday ........

4.She did not stop learning German until the age of 24.

=>It was not until ..........the age of 24 that she stopped learning German ........

=>Not until.......the age of 24 did she stop learning German ...........

5.I could not finsh my project until Mark helped me.

=>It was not until.............Mark helped me that I could finish my project .................

=>Not until..........Mark helped me could I finish my project .......

6.I did not sleep until midnight.

=>It was not until......midnight that I slept ............

=>Not until...............midnight did I sleep ....................

7.They did not pay the bill until the electricity was cut off.

=>It was not until.......the electricity was cut off that they paid the bill ...........

=>Not until.......the electricity was cut off did they pay the bill .......

8.I could comment further until I had all the information.

=>It was not until.............I had all the information that I could comment further .......................