The sentences describing concentration are as follows:

1. He listened to the teacher's explanation attentively, as if the whole world had disappeared, only his and the teacher's voices.

2. Xiaohong is concentrating on completing her painting. No matter who disturbs her, she will ignore it.

3. The scientists were concentrating on studying the new experimental results and did not notice the passage of time.

4. The students listened attentively for fear of missing any important information.

5. He observed the old painter attentively, trying to learn his techniques and style.

6. Although the environment was noisy, he still concentrated on reading, as if everything had nothing to do with him.

7. The musician played his instrument with concentration, immersing the audience in the beautiful music.

8. She concentrated on preparing her speech, hoping to achieve good results in the competition.

9. The children watched the magic show attentively and were deeply attracted by every magical moment.

10. He looked at the painting intently, as if looking for something hidden in it.

11. Xiaoqiang's eyes widened in anger, his eyebrows stood up, his hair stood on end, and a harsh sound came out of his mouth. Not only that, he also stretched out his hand to hit Xiaoqiang. The flushed face looked like a ripe tomato, and the body pounced like a lion.

12. Sun Qiang took a few steps towards the door, tears falling like broken pearls.

13. Think hard and concentrate.

14. I lowered my head timidly, not daring to look at my father’s cloudy face.

15. Her father agreed to her request, and she was immediately elated, joy flew to her brows, and her eyes narrowed like two small crescents.