1. The school girl in red is my sister.

2. The boy under the tree is my brother.

3. The students in the front of the classroom are from my class.

4. Playing football is my favourite.

5. To do homework first after school is my duty.

6. Those who help themselves can get help from God.

7. The sun is shining.

8. The river flows.

9. The flowers bloom.

10. The children play.

这些句子中的主语都是名词短语，每个句子都描述了一个场景或状态。希望这些例子对你有所帮助。