Syntax

Syntax: it refers to different constituents combined to form sentences in a language.
All and only: we create rules based on well-formed structures. And then, we have to apply these rules whether is applied logically or won’t lead to ill-formed structures.
Deep/Surface Structure
Some superficially similar sentences are in fact different. For example, active voice and passive voice. I like the cat. The cat is liked by me.
Some superficially different sentences are in fact similar. For example, I saw a girl who wore a pair of binoculars. By using a pair of binoculars, I saw a girl. These two deep sentences can be represented in the same surface structure form: I saw a girl with a pair of binoculars.
Recursion: 1. To put another sentence inside it. 2. A phrase can be repeated endlessly.
Back to recursion: it can be described as some phrase structure rules.

Tree Diagrams
Phrase Structure Rules
NP 1. Art (Adj) N 2. PN 3. Pro
VP 1. V NP (PP) (Adv)
S 1. NP VP

Lexical Rules
We rely on lexical rules to generate the grammatical sentences.
Movement Rules
We should study hard. Should we study hard?
1. NP Aux VP Aux NP VP

2. Active voice transforms into passive voice
Active NP1 VP NP2 NP2 be V-ed by NP1 (passive)