
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
$(1)$ Simplify: $2m+3n-3m+5n$;<br/>$(2)$ Below is the process of Little Le's simplification of polynomials. Please read carefully and complete the corresponding tasks.<br/>Solution: $2(m^{2}+m^{2}n)-(2m^{2}-mn^{2})$,<br/>$=2m^{2}+2m^{2}n-2m^{2}+mn^{3}\ldots $, first step,<br/>$=3m^{2}n\ldots $, second step.<br/>Task $1$: Fill in the blanks: In the above simplification process, the error begins in step ____, and the specific error is ____;<br/>Task $2$: Please write down the correct simplification result directly, and calculate the value when $m=-4$, $n=-\frac{1}{2}$.

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