We may find that learning a foreign language does not have to be________learning our mother tongue,but can in fact be twice ________.
The flu is believed ________ by viruses that like to reproduce in the cell inside the human nose and throat.
________ the meeting himself gave them a great deal of encouragement.
—They are quiet,aren't they?—Yes.They are accustomed ________ at meals.
The news of ________ greatly made us surprised a lot as he was indeed very excellent.
________ the program,they have to stay there for another two weeks.