| 1 | This question is more difficult than the last one. | |
| 2 | This problem is too difficult, I don't know how to do it. | |
| 3 | This question is too complicated, I have to solve it patiently. | |
| 4 | This math problem is definitely not easy, you need to think carefully. | |
| 5 | This problem is too difficult, I need more time to think about it. |