What is the population of America — I don’t know. But I know it’s than that of China.

We are confident that the environment ______ by our further efforts to reduce pollution.

s in hospital.—Oh, really I _____ know ,I ____ go andvisit her.

When ________ what his problem was, the boy lowered his head and kept silent[ ]

It’s easy __________you to saysorry, but remember __________ be late again.