I need you to help me analyze this experimental procedure converted into imperative sentences. What would be the verb placed at the beginning of the sentence?
Please note: 
1. Only need to output one English verb word, such as "CLEAN"
2. Please retain the core actions of the experimental procedure.
3. If this experimental procedure serves as a description and there are no actual executable actions, please output 'NONE'.
The experimental procedure is as follows:
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