—Who______ it be that is knocking at the door?
—It ______ be Father, but I’m not sure.
| A．can; must | B．can; may | C．must; can | D．may; must |
_____ a family of chimps wake up is our first activity of the day.
| A．To watch | B．Watching | C．Watch | D．Watched |
Earlier that day, when they crossed the Rocky Mountains, they ____ to catch sight of some mountain goats and even a grizzly bear and an eagle.
A. tried B. had C, managed D. surrounded
. It is so wet there that the trees are extremely tall, some _____ over 90 metres.
| A．measure | B．measured | C．measures | D．measuring |
. Skiing in the Rocky Mountains and sailing in the harbour make Vancouver one of Canada’s most popular cities _____.
| A．to live | B．to live in | C．lived | D．living |
People say it is Canada’s most beautiful city, _____ by mountains and the Pacific Ocean.
| A．surrounding | B．surround | C．to surround | D．surrounded |