Half of the books ________easy for the students to read．　 

Here _____a set of keys.The keys _____Bob’s.

.One out of three villagers                  a new school in the village.

Across the Yangtze River ______ more than one bridge, the Nanjing Changjiang Bridge being the first one.

The company used 50 percent of the raw materials, the rest of which __________ sent to other cities to help the factories there.