
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
Among the following four propositions:  
① A pyramid with an equilateral triangle as the base and isosceles triangles as the lateral faces is a regular pyramid;  
② There are 4 planes that are equidistant from four non-coplanar points;  
③ The lateral faces of a regular tetrahedron are acute triangles;  
④ In an ellipse, as the eccentricity $e$ approaches 0, the shape of the ellipse tends to be more elongated.  
The numbers of all true propositions are ▲ .

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