Do you know why the river was polluted? — Many different factors ___________ the serious pollution of the river.

— Who should be responsible for the accident?— The boss, not the workers They just carried out the order_____ [ ]

You shouldn’t go out without a coat , it’s rather cold

I can’t believe that Jeff _______ have quarreled and fought with his boss.— Well, if one _______ ask for trouble, it just can’t be helped. [ ]

I’m so glad you’ve come here to ________ this matter in person. [ ]