
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 200 products, there are 192 first-grade products and 8 second-grade products. The following events:  
① Randomly selecting 9 products from these 200, all are first-grade;  
② Randomly selecting 9 products from these 200, all are second-grade;  
③ Randomly selecting 9 products from these 200, not all are first-grade;  
④ Randomly selecting 9 products from these 200, the number of non-first-grade products is less than 100,  
Among these, \_\_\_\_\_\_ is a certain event; \_\_\_\_\_\_ is an impossible event; \_\_\_\_\_\_ is a random event．

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