Mr. Duncan raised an unnecessary question__________-he then failed to find an answer.

Mr Green didn’t know ______ last night.

Do you find this Maths problem__________?—Yes. I can work it out_______.

Hello, this is Jack. May I speak to Tom?– Sorry, he isn’t in at the moment. If he _______ back, I’ll ask him to call you back.

Will there be more people in the future ? — No, ________. There will be fewer people.