Final answer:
The question relates to safety requirements that students must meet before engaging in hands-on vehicle or operator training, likely including supervision and protective gear.
Step-by-step explanation:
The question asks which conditions must be met before students can participate in hands-on vehicle or operator training. Typically, this would involve specific safety requirements, such as having proper supervision or wearing the necessary protective gear.
Without more context, it's difficult to provide the exact words that would complete the sentence. However, in most cases, safety training programs require students to have supervision by a qualified instructor and the use of appropriate safety equipment before undergoing any practical training.