It is reported that the drivers who use mobile phones while driving are more ______ to have accidents.

—John always thinks of others instead of himself.—So she does. It is __________ of him to offer help to others.

In the new curriculum, some courses are        , while others are optional for middle school students.

When he came into the dining hall, nobody said hello to him. So he felt      .

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