Many clothing manufacturers now substitute artificial silk _____ natural silk to cut down costs of production．
| A．with | B．by | C．for | D．of |
As is well known to us all, in China pigeons stand for peace. However, in India the wheel in its national flag is also a _______of peace.
| A．symbol | B．sign | C．mark | D．example |
It doesn’t make a(an)_______to me whether you go or stay.
| A．difference | B．point | C．deal | D．effort |
How did it______ that humans speak so many different languages?
| A．come out | B．come off | C．come about | D．come round |
Eric was well prepared for the computer test so that he could be positive about passing it on his first________.
| A．intention | B．attempt | C．purpose | D．desire |
I was ashamed____ my failing the exam and decided on a measure to make up for it.
| A．of; upon | B．for; on | C．at;on | D．about; upon |