________ we admit that there are still some problems about the system of modern education,we don’t mean that it is of no use.
—How long are you staying? —I don’t know. ______.
Whatever work you are doing, you should concentrate your attention ______it.
The incomes of skilled workers went up. _____, unskilled workers saw their earnings fall.
______in a proper way, waste can be turned into useful things.
It’s helpful to put children in a situation______ they can see themselves differently.