______ it is true that a student’s most important goal is to do well in his or her studies, it doesn’t need to be the only goal.
| A．When | B．As | C．While | D．Before |
When ____ comes to saving energy, big changes start with small steps, like turning off the lights.
| A．that | B．this | C．it | D．one |
Of the two cameras, I would prefer_____ one, which is very easy for me to carry.
| A．a smaller | B．the smallest | C．a small | D．the smaller |
Mr Jones, a professor, ____ for his excellent lectures, is popular with his students.
| A．known | B．knowing | C．to be known | D．having known |
—Can you give some advice on what I said just now?
—Sorry. My mind____.
| A．is wandering | B．was wandering | C．has wandered | D．had wandered |
Having____ no-meat day would be a good way of encouraging ____ low carbon life-style.
| A．a; the | B．a; a | C．the; the | D．the; a |