—Look! A book is on the floor. Whose is it?—It ______be Rick's. It has his name on it.
— useful invention it is.—Yes, It helps us a lot.
—Tom has made great progress this term.— , and .
The bike boy fixed up all the bikes then he ______ to the poor children .
_______ has donated much money to the charity .
---.Look! It _____be your uncle .----It_____ be him . He has gone to Xi’an.