
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
Is the following statement correct?  
① $a^2 > 4$ is a sufficient condition for $a > 2$;  
② $(x+1)(x+2)=0$ is a necessary and sufficient condition for $x=-2$;  
③ $a^2 \neq b^2$ is a sufficient condition for $|a|=|b|$;  
④ $a < b$ is a necessary condition for $ac^2 < bc^2$.  
Please fill in the correct serial numbers on the line.

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