I urgenlty need you to check these sentences, too. I need to be extremely convincing but also determined.

1) We also agreed to use English as lingua franca during the preliminary meeting we held at our school with our school principals.
2) On that occasion we established that all the emails, the official communications and written reports were to be written in English.
3) Outside the project students can talk in the language they like most.
I therefore hope you will let me vary the various instances of "foreing/modern/European languages" you included in F4/D3/D4 or with English.
4) Being a science project, the language must be English also because the scientific terminology is in English and there is no point in translating it into other languages.
5) We keep emailing us in English because we both agreed to use English as lingua franca.
6) Our science teachers don't know either French or German,too.
Please, let me vary the application module otherwise my students won't be able to join in.

1) We also agreed to use English as lingua franca during the preliminary meeting we held at our school with all the schools' principals.

2) On that occasion, we established that all the emails, the official communications, and the written reports were to be written in English.

3) Outside the project, students can use the language they like most; therefore, we must edit the various instances of "foreign/modern/European languages" you included in F4/D3/D4 or with English.
(I don't understand the underlined part.)

4) Since this is a science project, the language must be English because the scientific terminology is in English, and there is no point in translating it into other languages.

5) We keep emailing among ourselves in English because we both agreed to use English as the lingua franca.

6) In addition to all that we had previously agreed on, our science teachers don't know either French or German. Therefore, we must vary the application module; otherwise, my students won't be able to participate.

1) This sentence appears to be grammatically correct. To ensure it is convincing and determined, you can consider adding more specific details or reasons behind the decision to use English as the lingua franca. For example, you could mention the advantages of using English for effective communication or how it will enhance the project's outcomes.

2) This sentence seems grammatically correct. To make it more convincing and determined, you can emphasize the importance of using English for official communications and written reports. You may want to mention how using a single language will ensure clear and consistent communication among all project participants.

3) This sentence is grammatically correct. To further emphasize your determination, you can mention the benefits of allowing students to freely choose the language they prefer outside of the project. This flexibility can foster inclusivity and encourage active participation from all students.

4) This sentence appears to be grammatically correct. To strengthen your argument, you can provide additional reasons why using English as the language of the project is essential. For example, you can mention that using English will allow students to access a wider range of scientific resources and collaborate with experts in the field.

5) This sentence seems grammatically correct. To make it more convincing and determined, you can highlight the commitment of both parties involved in the email exchange to use English as the lingua franca. This emphasizes the importance of consistent communication and ensures that both parties can fully understand each other.

6) This sentence appears to be grammatically correct. To enhance the conviction and determination, you can explain the significance of the science teachers' lack of knowledge in French or German. Emphasize how this further reinforces the necessity of using English for effective communication among all project participants.

Overall, to make your statements more convincing and determined, it is important to provide clear and logical reasons behind the decisions and language choices.