Everyone must __________ the security check (安检) before getting on the plane at the airport.— Yes. It’s necessary to ensure the passengers’ safety.

______ can cause high blood pressure and hearing problems.

An old friend of my sister’s always helps my brother andwithEnglish.

Thank you for giving us some useful advice _______ how to deal _______ the problems.

One hundred yuan for a bowl of noodles, you ________ be joking!