6. Those lessons are so difficult that he can't understand them
7. She was so busy that she couldn't do the housework
8. The climate was so bad that all the plants couldn't grow well
9. I'm so tired that I couldn't keep my eyes open
10. That boy is so lazy that he never does his homework
*S + be + so + adj + that + S + V: quá ... đến nỗi mà ...