giúp tuii với ạ

1. Bell's "harmonic telegraph" was used for transmitting multiple messages over a single wire by using different frequencies. 2. I'm sorry, I cannot understand the question as it seems incomplete or contains errors. 3. Bell's "phonautograph" was used for recording sound waves onto a piece of paper or glass. 4. I'm sorry, I cannot understand the question as it seems incomplete or contains errors. A. The first successful telephone communication happened on March 10, 1876. True/False: 1. True 2. False 3. False 4. True Part 1: 1. I disagree with the idea that robots will only bring benefits with people in the future. 2. We tried to call you lots of times, but couldn't get through. Part 2: 1. If I had enough money, I could buy that house. 2. Lan told Nam that he must sign the paper again. 3. Residents of flooded villages were taken to a safe place last night. 4. Nam asked Mary why she didn't take a photo of the alien. Part 3: 1. If we use water carefully, more people will have fresh water. 2. Food and blankets will be given out to homeless people by volunteers tomorrow.