Question

Ling built a circuit with three light bulbs. She observed that all three light bulbs glowed.

Answer 1

Answer:

Put the light bulb that was removed back into the circuit and observe whether the other lights come on.

Explanation:

If all three bulbs initially glowed and she supposes that after removing the first bulb, the others stopped glowing because they burned out, then she must replace the original bulb and see if the other two bulbs will glow.

If all three bulbs don't glow after replacing the first one, then all the bulbs may have probably burned out.