While he was investigating ways to improve the telescope, Newton made _______ discovery which completely changed _______ man’s understanding of colour.
| A．a；/ | B．a；the |
| C．/；the | D．the；a |
—I find it astonishing that your deskmate ________ be so rude to you.
—Not astonishing at all. She is always rude to anyone else.
| A．should | B．must | C．might | D．ought to |
－It's getting dark. I must be off now.
－OK, please take care and ________ my best wishes to your family.
| A．accomplish | B．clarify | C．preserve | D．Convey |
The education program ________combining brain work with manual labor is being widely spread throughout the country.
| A．to aim at | B．aims at |
| C．having aimed at | D．aimed at |
Even in winter the roadsides were places of beauty, ________ countless birds came to feed on the berries and on the seed heads of the dried weeds rising above the snow.
| A．which | B．when | C．where | D．What |
--- Look at the sweat on her face.
--- She ________ the house since she got up this morning.
| A．is cleaning | B．has been cleaned |
| C．was cleaning | D．has been cleaning |