They received demands that the work ________ at once.

--Pity you missed the lecture on nuclear pollution.-- I ___ it, but I was busy preparing for a job interview.

 If human beings had been a bit less greedy and cruel, more birds and animals _______dying out.

— Do you know where David is ? I couldn’t find him anywhere. — Well. He ______ have gone far –his coat’s still here. 

_______ he was seriously ill, I wouldn’t have told him the truth.