—Where have you been recently? —I ________ in Hangzhou on business for a week last month.
I saw him _______ out of the room.
They would not allow him ________ across the enemy line.
The workers want us ________ together with them.
He walked along in the _____hoping no one would recognize him.
In ____late 19th century, Europe changed ______great deal and played an important role in ______international trade.