I want to write you a 400-word composition.

When writing the composition I want to tell you, you can start from the following aspects:

1. Express gratitude: First of all, you can express your gratitude to the other party for their concern and support. 2. Praise each other's advantages: Secondly, you can praise each other's advantages, such as their selfless dedication and hard work.

3. Express gratitude: Finally, you can express your gratitude again, thanking each other for their love and concern.

4. Express your expectations for the future: You can express your expectations for the future at the end of the letter. I hope we can keep in touch and make progress together, and wish each other health and happiness.