We ________ the difficulty together，but why didn't you tell me?

——My cat’s really fat. ——You____________have given her so much food. 

If the firefighters ________ in time, the fire would have resulted in many deaths in the hotel.

John agreed to the suggestion that his students _____ two weeks to prepare for the exam. 

The project ______ last month but unfortunately it had to be prolonged because of the financial problem.