My friend warned me ______ going to the East Coast because it was crowded with tourists.
| A．by | B．against | C．on | D．for |
Could you give me the phone number of _____ David Cooper on _____ Fifth Avenue?
| A．a ; the | B．a ; 不填 | C．不填；the | D．the ; the |
Without the earth’s atmosphere to protect them, astronauts can be exposed to intense radiation from the sun, ____ them at risk of cancer.
| A．to leave | B．leaving | C．having left | D．left |
If there were no automatic washing machines, people would have to wash their clothes ______ hand or ______ hand-operated machines.
| A．by; by | B．with; with | C．on; with | D．by; with |
“No bread eaten by man is so sweet as______ earned by his own labour. ”
| A．one | B．that | C．it | D．those |
_____ the majority of people you will meet when travelling are sure to be friendly, there are dangers-theft being the most common.
| A．Since | B．Unless | C．While | D．Once |