Mr. Keller _________ forty cigarettes a day until he gave it up.
| A．had smoked | B．smokes | C．have smoked | D．smoked |
Every day ________ a proverb aloud several times until you have it memorized.
| A．read | B．reading |
| C．to read | D．reads |
All flights ________ owing to the heavy fog, many passengers could do nothing but take trains.
| A．to be cancelled | B．were cancelled |
| C．have been cancelled | D．having been cancelled |
The poem A Red, Red Rose written by Robert Burns is popular with the Chinese young people, because the poem is easy ________.
| A．to be understood | B．to understand |
| C．understand | D．understanding |
Passengers are permitted______ only one piece of hand luggage onto the plane.
| A．to carry | B．carrying |
| C．to be carried | D．being carried |
Bats are surprisingly longlived creatures, some______ a life span of around 20 years.
| A．having | B．had |
| C．have | D．to have |