According to the school rules, no child _______ be allowed out of the school during the day, unless accompanied by an adult.
Some insects ______ the color of their surroundings to protect themselves.
The living room is clean and tidy, with a dining table already ______ for a meal to be cooked.
Sam _____ some knowledge of the computer just by watching others working on it.
That’s the new machine ______ parts are too small to be seen.
—Do you think you could do without help? —______. This is not the first time for me.