I don't know.How can I make the vegetables grow so well?

问题描述:

I don't know.How can I make the vegetables grow so well?
把这个句子合并为宾语从句

I don't know how I can make the vegetables grow so well.一般宾语从句不是要加that之类的引导词吗?加不加都可以,一般情况下可以省略。