Scientists say it may be five or six years _____ it is possible to test this medicine on human patients.

—Do you remember          he came?—Yes, of course. He came by train.

The chairman declared that ________ player scores the highest number of points would be the winner.

There is a common belief among them ________ rubbish can and should be put to good use.

______ you'll be able to succeed mainly depends on ______ you do and ______ you do it.