---What are you busy with ?
--- We are carrying out a research ____ the causes of cancer.
| A．into | B．onto | C．to | D．in |
In that school, English is compulsory for all students, but French and Russian are ______.
| A．special | B．regional | C． optional | D．original |
Would you like tea or coffee?
--_____, thank you. I’ve just had some water.
| A．Either | B．Both | C．Any | D．Neither |
We can never expect ____ bluer sky unless we create _____less polluted world.
| A．a; a | B．a; the | C．the; a | D．the; the |
—Can I use your laptop for a while?
—; any how I am not using it now.
| A．That’s OK | B．By all means | C．It doesn’t | D．Use it. |
What the science teacher does and says of great importance to college students.
| A．are | B．is | C．were | D．was |