Question

regarding maintenance and lubrication, most drills do not require periodic lubrication must be lubricated every 30 days must be lubricated every 90 days must be lubricated more often when drilling metal

Explanation:

To solve this, we analyze each option:

• Option 1: Most drills do require periodic lubrication, so this is incorrect.
• Option 2: There's no standard that drills must be lubricated every 30 days; lubrication frequency depends on use, so this is incorrect.
• Option 3: Similarly, there's no rule that drills must be lubricated every 60 days; this is incorrect.
• Option 4: When drilling metal, friction and heat increase, so more frequent lubrication (to reduce heat, wear) is needed. This matches practical knowledge about drill maintenance.

Answer:

D. must be lubricated more often when drilling metal