No matter how frequently __________, the works of Beethoven still attract people all over the world.
| A．performed | B．performing |
| C．to be performed | D．being performed |
Why ____ you keep on troubling me with such questions while I''m busy ?
| A．could | B．can | C．must | D．will |
I saw him leave the office an hour ago . He ____ at this time .
| A．mustn''t be working | B．can''t be working |
| C．can''t work | D．may not being working |
You don''t look well . You ____ have a fever .
| A．might | B．can | C．shall | D．should |
He studied hard and ____ pass the examination .
| A．could able to | B．could | C．was able to | D．ought |
The money was soon spent , so he ____ go hungry .
| A．must | B．had to | C．might | D．should |