Three million tons of coal ______ every year in the city.
The classroom is big enough________,but we'll have to move if we have more students.
Through the window,we can see his large house________.
Mr.Smith as well as two of his students ________ the experiment with care at the moment.
A lot of banks are ________ to the new electronic system because it's more efficient.
The role that women have been ________ in human history is of great importance.