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4. Here's the categorization of the ideas: Advantages: - a. They're cheap or even free. - c. You can talk to people from distant places. - e. You can make group calls. Disadvantages: - b. There must be an Internet connection. - d. You may receive unwanted calls. - f. You need a smart device. 5. Example Discussion: I think there are both advantages and disadvantages of online calls. On the one hand, online calls are cheap or even free, which is very convenient for people who want to save money on their phone bills. We can also talk to people from distant places and make group calls, which is very useful for business or study purposes. On the other hand, online calls require an Internet connection, so if the connection is poor, the call quality may be affected. Moreover, we may receive unwanted calls, which can be annoying and disturbing. Additionally, we need a smart device to make online calls, which may not be accessible to everyone. Overall, I think the advantages of online calls outweigh the disadvantages, but it's still important to be aware of the potential drawbacks.