48.Plant more trees every year and the desert will become green in a few years' time.

If you plant more trees every year,the desert will______ ______ with green trees in a few years' time.

47.Bob's lonely because it's difficult for him to make friends.

Bob's lonely because he______ ________at making friends.

46.There's nobody but a passenger in the bus.

There's______ one passenger in the bus.

45.Bob had no teacher,but he learned English well at his young age.

Bob________ ______English when he was young.

44.This book has nothing to do with English.

This book is_____ _______English.

43.There are more people in this city than in that city.

The _____ of this city is_______than _____of that one.

42.This book isn't as interesting as that one.

This book is _______interesting than that one.

41.The heavy rain stopped them from leaving home.

The heavy rain_______ them _______ at home.

40.Please don't make our room dirty.

Please _____ our classroom____.

39.The doctor told him to stop smoking.

The doctor told him to _____ _______smoking.