—— He promised to come to see you. —— But he ＿＿＿＿＿. I’ve been all alone. 

——He ought to have been warned of the danger. ——____, but he wouldn’t listen to me.

Not until I dropped off from school ____ how much time I had wasted.

_____ is necessary for us to tell him about the result.

Some seemingly harmless blogs might become harmful when ________ on the Internet by millions of people.