
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 surveys, those that require a census are: (Fill in the serial number)  
① Understanding the vision situation of middle school students in a certain city;  
② Understanding the health situation of people over 100 years old in a certain city;  
③ Understanding the extracurricular reading situation of middle school students in a certain city;  
④ Understanding the annual income situation of all families in a community.

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