He was absent for weeks, so he had a lot of homework to ________.
—— Your father is very strict with you. ____. He never lets off a single mistake of ours.
No sooner ____ to the station ____ the train left.
If you don't go, neither ____.
Only by practising a few hours every day ____ be able to master the language.
Not until I began to work ____ how much time I had wasted.