
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 that $a$ and $b$ are non-perpendicular skew lines, and $\alpha$ is a plane, then the projections of $a$ and $b$ on $\alpha$ could be:  
① Two parallel lines; ② Two perpendicular lines;  
③ The same line; ④ A line and a point outside of it.  
Among the conclusions above, the correct ones are

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