
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
Suppose we have a function $f(x)=\ln x- \dfrac {1}{2}ax^{2}-2x$, where $a\leqslant 0$.
(Ⅰ) If the tangent line to the curve $y=f(x)$ at the point $(1,f(1))$ is $y=2x+b$, find the value of $a-2b$;
(Ⅱ) Discuss the monotonicity of the function $f(x)$;
(Ⅲ) Let $g(x)=x^{2}-3x+3$ be another function. If for any $x$, $t∈[0,1]$ it holds that $f(x)\leqslant g(t)$, find the range of the real number $a$.

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