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1. None of them could not answer the questions, asked by the tutuor.
2. Any of these questions were worth discussing.
3. What are there in the middle of your room?

1. None of them could answer the questions, asked by the tutuor.
(или) All of them could not answer the questions, asked by the tutuor.
2. Some of these questions were worth discussing.
3. What is there in the middle of your room?