I left out these last sentences. Thank you very much.
1) I was having dinner / I had been having dinner when the telephone rang.
(If the two actions happen at the same time only the past continuous is possible)
2)I'm going to go on a scout camp for two weeks.
I'm going to stay there with forty other students in the age from ten to sixteen.
3) I have't heard from you for a more than a week. I really hope you'll reply to my last email. Next week my workmates will report about their partners to me. It is extremely important for us to get to know your opinion about the partnership.
4) You'll have to keep your money handy because the sales representative will be delivering the books to you by the end of this week.
You'll need to collect the money by tomorrow.
1) I was having dinner / I had been having dinner when the telephone rang.
(If the two actions happen at the same time only the past continuous is possible) <~~correct
2) ... with forty other students ages ten to sixteen.
3) OK
4) OK
1) The first sentence is discussing an action happening in the past while another action interrupts it. In this case, having dinner is the ongoing action and the telephone ringing is the interruption. To determine which tense to use, we need to understand the sequence of events. If the two actions happened at the same time, only the past continuous tense ("I was having dinner") would be possible. This is because the past continuous tense is used to describe an ongoing action in the past. If the telephone rang before you started having dinner, then "I had been having dinner" would be more appropriate. To determine the sequence of events, we would need a further context or information.
2) The second sentence is discussing future plans to go on a scout camp for two weeks. You mention that you will be staying there with forty other students aged from ten to sixteen. There's no particular question associated with this sentence, but it's possible that you might want to inquire about something related to the camp or the stay.
3) The third sentence expresses the fact that someone has not heard from another person for more than a week. It also mentions the hope for a reply to a previous email and the importance of receiving the person's opinion about a partnership. Again, there's no specific question here, but if you are looking for advice on how to approach the situation or if there's any particular information you need regarding communication and conveying the importance of a response, feel free to ask.
4) The last sentence provides instructions or advice regarding money management. You are advised to keep your money handy because a sales representative will be delivering books to you by the end of the week. Additionally, it is mentioned that you need to collect the money by tomorrow. If you have a question about why the money needs to be collected by tomorrow or if there's any specific guidance you need in dealing with the sales representative or managing your finances, feel free to ask.