Bamboo, which is a common plant in the south, is used ______ in buildings, food, furniture and so on. It is used to make clothes as well.

In the park , the number of the visitors is tightly ____ to avoid damaging the environment or putting stress on the animals.

He was watching her doing it with a _________ look on his face, as if to say that he would not change his mind.

Although the increase in the present sum used for the research is________， a great breakthrough could still be achieved by the end of this year.

Oh, boy, why are you just playing games all day? Can't you find something ______ doing at all?