She was so upset by the accident that she couldn’t ________ to explain just what happened. [ ]

Helen was much kinder to her youngest child than she was to the others，，of course，made the others jealous．

____ is known to us all is that the old worker, for _____ life was hard in the past, still works hard in his seventies.

You can hardly see anything in the dark room, ­­­_____

The number of people who______ English as a foreign language_______ more than 750 million.