In communication, a smile is usually _____ strong sign of a friendly and _____ open attitude.
| A．the; / | B．a; an | C．a; / | D．the; an |
Professor Smith, along with his assistants, _____on the Project day and night to meet the deadline.
| A．work | B．working |
| C．is working | D．are working |
He met his previous teacher ________ at abroad.
| A．by any chance | B．by the chance |
| C．by chance | D．by a chance |
Tom, ______ yourself .Did you forget the school rules?
| A．behave | B．believe |
| C．perform | D．conduct |
He is the only one of the students who ______a winner of a scholarship for three years.
| A．is | B．are |
| C．have been | D．has been |
Though having lived abroad for years, many Chinese still ______ the traditional customs.
| A．perform | B．possess |
| C．observe | D．support |