It is generally believed that Watson and Crick’s discovery about DNA was ____ beginning of _____ enormous advances in _____ field of genetics.
| A．the, the, the | B．/, /, the |
| C．the, /, the | D．the, the, a |
Do swim with others. Otherwise, you .
| A．can get drowned | B．will get drowned | C．might have got drowned | D．might get drowned |
As is known to all, to smoking will do harm to your health.
| A．addicted | B．having addicted | C．being addicted | D．after being addicted |
the exploration of the botanical world on a large scale.
| A．It was not until the eighteenth and nineteenth centuries that; had begun |
| B．It was not until the eighteenth and nineteenth centuries when; began |
| C．Not until the eighteenth and nineteenth centuries did; begin |
| D．Until the eighteenth and nineteenth centuries; began |
How do you think that he was an hour late on such a short journey?
| A．it came about | B．did it come about | C．it was come about | D．was it come about |
If I yesterday, he now.
| A．had said sorry to him, wouldn’t be angry | B．said sorry to him, wouldn’t have been angry |
| C．have said sorry to him, won’t be angry | D．had said sorry to him, would be angry |