At that time I had no idea _________ I could hand it to him without being seen.
______ the ancient Egyptians built the pyramids puzzled people for centuries.
______ I’m well again, I can go on with my work.
The government has to close those small factories to prevent the water of the river ______.
We should try our best to ______ those people after the disaster.
------We want someone to design the new art museum for us. ------______the young fellow have a try?