The number of teachers in our school _______ greatly increased last term.A number of teachers in this school ______from the countryside.

Days later, my brother called to say he was all right, but ________ say where he was. 

—Look! A book is on the floor. Whose is it?—It ______ be Rick’s. It has his name on it.

--Guess what! Tan Weiwei failed in the last round of the Super Girl Contest.---How _______ it be? She is second to none in singing in my opinion.

The weather turned out to be fine. I       the trouble to carry the umbrella with me.