I knew I could not finish the homework _____

Only when he failed in the final exam ____up his mind to study harder to catch up with the classmates ahead of him.

The notice has been told to everyone _______ a partywill be held in the open air tomorrow．

He appears to be optimistic, but, ______, he is quite pessimistic

_____ she had not spelt the word wrong, Cathy would have got a full mark. [ ]