_____ worries the doctor most was _______ they could find the cause of the disease.
The old man lives alone on an island, and his home is not accessible ______ by boat.
Do you think it ______ to attend the summer training courses run by the Sunday school?
Jim is old enough to look after the pet dog ______.
I never dreamed of ______ such a big crowd here.
Many famous writers are reported ______ long before they started reading themselves.