
Ruediger T. answered 08/14/21
Language expert - German, English, French - 30 years experience
The importance of syntax can't be stressed enough, especially if your native language differs greatly from English. To the left of an English verb is the subject and to the right of it is the object. An English sentence like the ball kicked the boy is perfectly grammatical even though you have never heard of balls who kick boys.
Consider these two basic facts about English syntax: Its basic form is Subject-Verb-Object or SVO for short, and neither the subjects nor the objects are morphologically marked (= their form does not change except in some pronouns). This means, and to native English speakers this will perhaps sound crazy, that in a statement like Cain killed Abel the only way we know who killed whom (here you have a marked object pronoun) is by looking what/who is to the left of the verb - killed - and what/who to the right of it.
Now imagine a language that has OVS syntax (Object-Verb-Subject) instead of SVO. You'd have to swap the brothers or the same statement would mean that it was Abel who killed Cain.
Or consider a language like German, where subjects and objects are often morphologically marked (the cases) and syntax (=word order) is therefore much freer than in English. In German you can swap the position of subject and object and say for example den jüngeren Bruder erschlug der ältere Bruder. A word-for-word translation that would not account for syntax would yield the younger brother (Abel) killed the older brother (Cain), contradicting the biblical story.
So the short answer is: without an understanding of syntax the L2-student would be lost.