Please choose the correct ending to complete the given sentence: Youth: [header] How to use laser pointers safely [title] Never point your laser at another person, especially their face. [step] Laser pointers are very useful, but are a serious hazard to the eyes if used improperly. While lasers under five milliwatts are unlikely to cause significant injury, staring directly into the beam can cause a dark spot, or burn, on your retina.

Ending1: Always and always use an electronic concealing device such as a helmet or visor when using laser pointers. [substeps] Otherwise, use your eyeglasses and goggles when applying laser pointers. Ending2: The bright light of the beam can also distract someone while driving or operating aircraft. [substeps] Be aware of the beam at all times. Ending3: [title] Be sure to check your lenses often. [step] Although laser pointers cannot cause serious damage, they can cause a painful electric shock if they are placed in direct contact with someone's eyes. Ending4: To prevent yourself from burning yourself, try to maintain a relaxed, upright posture. [title] Apply a magnifying glass to the laser.

Answer format: ending1/ending2/ending3/ending4