| 1 | Or there was a relationship between work and heat. | |
| 2 | This problem is quite thorny to a certain extent. | |
| 3 | This theory is based on a certain physical principle. | |
| 4 | The gloomy look on his face indicated to people that he was in some kind of hardship. | |
| 5 | The results of this study indicate that the medication has good efficacy for a certain chronic disease. |