This part of the library is only ______ to people over eighteen years old.
With he help of his friends, he has _________ a good business over the years.
"We can't go out to play football in this rainy weather," said Bob, ________ out of the window disappointed.
The twins were so much alike; I could hardly ________ Tom.
By far, there are many problems ________ to be solved.
I don't think _________ possible to master a foreign language without much memory work.