ine bought a postcard of the placeshe was visiting, addressed _______ to _______ and then posted it at the nearbypost office

______ many students in China ever ______ to westerners before

His children are well-behaved, _____ those of his sister are naughty.[ ]

Various student clubs are set up in many senior high schools to urge students to ________ the opportunities to cultivate their good virtues and qualities.

The flu is believed _____by viruses that like to reproduce in the cells inside the human nose and throat. [ ]