It was the first time she had visited the National Gallery.
(never) She.....had NEVER visited... the National Gallery before.
Jenny didn't start cooking until after the children had fallen asleep.
(before) Jenny waited until the children.... had fallen asleep BEFORE she ....started cooking.
The last time I went to the theatre was months ago.
(have) I ......HAVE not been at... the theatre for months.
It's two months since she called me.
(has) She ...... HAS not called.... me for two months.
The president waited until all the reporters had arrived before he made his statement.
(making) The president didn't.......begin/start MAKING his... statement until all the reporters had arrived.
We haven't played chess for a month.
(since) It's a month .... SINCE we played.... chess.
Sue waited until Todd had left before she began packing.
(after) She didn't begin .....packing until after Todd had .....left.
Are you sure you want my help? It seems to me that this way you won't be able to solve such problems on your own, perhaps in a test that you will take in the future. Think about this... And I just love working out solutions to the problems like these!