While there are some differences in the education systems in many countries in the world, education is __________.

I think you should go back to your     plan, which is much more practical than the present one．

He is very popular among his students as he always tries to make them        in his lectures.

—The guard keeps         watch at the gate.—So he does. Only those         knows well could be let in.

The little boy still needs the________20 dollars to do with some things________.