—Your colleague's spoken English is beautiful, Lily．
—It's no wonder．She ____ in the USA for a year as a visiting professor．
| A．worked | B．has worked | C．had worked | D．has been working |
--- When did you last see your first teacher?
--- On ______ Friday last June, at ______ celebration of her 40th year of teaching.
| A．a; the | B．a; a | C．/; a | D．/; the |
Father made a promise ______ I passed the exam, he would buy me a PS4.
| A．if | B．that if | C．whether | D．that |
--- Alex came back home the day before yesterday.
--- Really? Where ______ at all?
| A．had he been | B．has he been | C．had he gone | D．has he gone |
The dangerous virus ______ in the next few weeks in the laboratory can cause fatal diseases.
| A．studying | B．studied |
| C．to study | D．to be studied |
How can you expect him to make any progress ______ you never give him a chance to have a try?
| A．when | B．unless | C．once | D．until |