根据句意，写出括号内所给单词的适当形式。
Do you think it’s good for you to keep worries to  _______ (your), boys and girls?
In China, it’s becoming much _______ (hard) for people to pass the driving tests.
The government has realized the importance of the _______ (safe) of the children who take a school bus.
More and more teachers feel worried about some _______ (teenage) strange behaviour.