The reason ______ Tom came to attend the meeting was ______ he was an expert in this field.
The dog, if trained _____, will be made a good watch-dog one day.
It is required that employees in the company have to have a good__________ of English.
We must keep on learning if we want to keep up with the ____ of the changing times.
If you are not happy with it, you should say it out. Don’t just ______ in silence.
A $1000 ____will be offered to anyone who helps to return the lost jewel .