_______he was laid off last year ______ how serious the economic crisis was.

--- It’s the fourth time that heavy smog(雾霾) has hit the city this month.--- It’s high time we _______ measures to fight air pollution. 

 I _____not thank you too much for your help. 

You can hardly imagine what great difficulty we had _________ the task.

It is difficult to judge whether what he said_________.