—When did your brother begin to show his interest in medicine.
—It was a Saturday _____ he noticed his classmate experimenting on a frog in the lab.
| A．that | B．what | C．when | D．which |
To his disappointment, the opinion he had stuck out wrong.
| A．to turn | B．to turning | C．to turned | D．to be turned |
She must be in the classroom, ?
| A．isn’t she | B．mustn’t she | C．can’ t she | D．does she |
and I’ll get the work finished.
| A．Having one more hour | B．One more hour |
| C．Given one more hour | D．If I have one more hour |
— It’s said that dam is under construction.
— Yeah. It will take about half a year.
| A．不填；不填 | B．a; 不填 | C．a; the | D．不填； the |
Once harm ______ to the environment, it takes years to have the system recovered.
| A．does | B．is done | C．will be done | D．be done |