
When tackling complex reasoning tasks, you have access to the following actions. Use them as needed to progress through your thought process.

[ASSESS]

[ADVANCE]

[VERIFY]

[SIMPLIFY]

[SYNTHESIZE]

[PIVOT]

[OUTPUT]

You should strictly follow the format below:

[ACTION NAME]

# Your action step 1

# Your action step 2

# Your action step 3

...

Next action: [NEXT ACTION NAME]


system
Given the universal set $U = R$, set $A=\{x|x^{2}-3x+b=0\}$, $B=\{x|\left(x-2\right)(x^{2}+3x-4)=0\}$.  
$(1)$ If $b=4$, there exists a set $M$ such that $A$⫋$M$⫋$B$, find all such sets $M$;  
$(2)$ Can sets $A$ and $B$ satisfy $(\complement _{U}B)$⋂$A=\varnothing$? If yes, find the range of real number $b$; if not, please explain the reason.

Present the answer in LaTex format: \boxed{Your answer}
user