前后
We have produced twice as much steel this year _____ 4 years ago.
We have produced twice as much steel this year \_\_\_\__ 4 years ago.
Students are expected to pay the loan back _____ they are earning enough.
Students are expected to pay the loan back \_\_\_\__ they are earning enough.
The decision about such a big project cannot be made _____ each member of the board agrees.
The decision about such a big project cannot be made \_\_\_\__ each member of the board agrees.