Please talk about the meaning of underlined sentences in the text in combination with real life.

1. Hard environment can temper people's will and become strong.

2. Therefore, if the sky is going to drop people, they must first suffer their will, work their bones and muscles, starve their bodies, empty their bodies, and mess with their actions, so their perseverance has benefited their bodies.

3. Refers to the tree's dependent lifestyle. Agreed. Because the hard environment can make people hone their strong will, and relying on life is not conducive to cultivating a strong and independent consciousness. When difficulties come, if they cannot be overcome, they will inevitably lead to disaster.

4. Contrastive writing skills are used to highlight the theme.