I have ________ homework to do in the evening.
It ______last week that the haze(雾霾) in Beijing caused many problems.
---Are you going to take part in the speech competition? --- _____. It’s too good a chance to miss.
Money is important in my life, but it isn’t_______ to me.
---There is somebody knocking at the door. Who________ it be?---I’m not sure. It ________ be a postman.
It’s clever _____ her to work out _____ many difficult math problems.