5道同义句转换1.This problem is so diffcult that I can't work it ou

5道同义句转换
1.This problem is so diffcult that I can't work it out.(划线部分为：so diffcult that)
2.I am going to my hometown tomorrow.
3.On Mother's Day,she sold out of the flowers.
4.Yao Ming took an interest in playing basketball when he was young.
5.People will plant trees to stop the sand storm.