The flu is believed____ by viruses that like to reproduce in the cells inside the human nose and throat.
—I wonder why he has been acting so strange these days. —Recent pressure at work may ______ his behavior.
At the meeting, they sat very_____ and had a _____ talk, but I didn’t know what they were talking about.
There was a very interesting remark in a book by an Englishman that I read recently ______ he thought was the reason for this American characteristic.
----- How about the book you are reading now? ----- Excellent indeed. You can find many problems we have come across _____ in it.
——Will you come to my office when youyour work? ——Sure.