语法和语感，相辅相承。 成年人学外语，从语法入手可以快速对此种外语有个大致了解，对语言学习很有帮助。不学语法，只能在大量的句子中自己总结出语法。 但语言不只是语法，不是学了语法就ok的，还需要大量练习。

Grammar is some knowledge you can learn and understand even with the help of your mother tongue, Chinese. Understanding this can be useful in English tests. But for writing and speaking, they are skills which you have to train yourself to acquire. When you write something or say something, you don't want to think about every word and revise every sentence like doing a test. So English tests and language skills are quite different things. 比如你标题的句子，能大概看明白什么意思，但是因为语法问题还是受一点影响，how to 后面是否应该有一个东西，how to solve? how do you think about? 所以语法掌握了以后，正确完整的表达是最基本的吧。