You ____ him so closely; you should have kept your distance.
| A．shouldn't follow | B．mustn't follow |
| C．couldn't have been following | D．shouldn't have been following |
His suggestion made me angry, but _______.
| A．making others happy | B．to make others happy |
| C．others happy | D．with others happy |
Generally speaking, my grandmother is nice and kind, but she _______ be very
stubborn at times.
| A．should | B．shall | C．must | D．can |
Most animals have little connection with animals of a different kind, _______ they hunt them for food.
| A．if | B．while | C．unless | D．as |
He loved his family, but seldom _______ spend much time with them.
| A．was he able to | B．he was able to |
| C．is he able to | D．he is able to |
A study shows that walking fast in your old age is a ______ that you will live a long life.
| A．sign | B．mark | C．symbol | D．signal |