.
Who did the teacher ________ the exercises?
| A．have done | B．have do | C．had done | D．has done |
—Tony, you must have noticed the student who broke the glass.
—I'm sorry.I________attentively.
| A．studied | B．was studying |
| C．am studying | D．would study |
—Sorry for the delay.I got lost in the mountain.
—That's OK.You're safe and that's what________.
| A．does | B．works |
| C．stays | D．counts |
—Tom has been fired by his boss.
—________？As far as I know，he is a hardworking and considerate fellow.
| A．Why not | B．How come |
| C．What then | D．So what |
Annoyed by the salesman's bad manner，John chose ________of the two computers on sale and left.
| A．all | B．either |
| C．neither | D．none |
People develop ________ preference for a particular style of learning at ________ early age and these preferences affect learning.
| A．a；an | B．a；不填 |
| C．不填；the | D．the；an |