Please check the list carefully ________________ make mistakes.

Two middle-aged passengers fell into the sea _______, neither of them could swim

Mark never considers himself as ________ failure. On the contrary, he thinks he is on the road to _______ success.

There’s not any beer left and the bar is shut so we’ll have to _______.

Look! The man at the gate _______be our headmaster. He is always standing there every morning.—No, it_______ be him. He is holding a meeting in the office now.