There was no room for you. All the seats______.

He volunteered to work in a remote mountainous village in West China last year, which is still _____ on foot now.

Is Jack on duty today — It ________ be him. It’s his turntomorrow.

The performance of this reasonably priced digital camera is _____ in quality to that of more expensive ones.

Paper money was in_______use in Chinawhen Marco Polo visitedthe country in________thirteenth century.