Although we haven’t got the accurate statistics, it is estimated that ______ 300 factories in this province closed down during the economic crisis.

The girl was so ____ by the mighty river that she would spend hours sitting on its bank and gazing at the boats and rafts going and coming. 

Americans eat_____vegetables per person today as they did in 1910.

With modern equipment，many mysteries have ________ to light in recent years.

The world’s population has grown by ______ it was in 1800.