STUDENT'S ASSIGNMENT
I think he is strange and silly.

TEACHERS COMMENT:
There's no wrong in your sentence but it would be better if you try to make more effective sentence. What is an effective sentence? Effective sentences have quality that enables them to convey an idea with clarity and style. They have a ring to them. They give the reader a sense  of what in them is most important. They do all this with a minimum of words.
Example of effective sentence using the word "strange".
1. Perhaps with these additions it would be too much to manage, still it does seem a bit strange.
2. The corridor smelled strange, it was the stench of the charnel house combined with the tang of powerful magic.
After all, I appreciate your sentence. like what I've said there's nothing wrong with that but there are always room for improvement. That's why teacher is here to help you. Thank You. T. Bernard :)