______ is known to us all , the old scientist,______ life was hard in the past, still works hard in his eighties.
As your spoken English gets better, so_____ your written English.
The boy insisted that he the money and he at once.
With more forests being destroyed, huge quantities of good earth _____ each year.
—Would you like to join us in playing the game? —I’m sorry, but my homework ______ by now.
Great as Newton was, many of his ideas _____today and are being modified by the work of scientists of our time.