Fill in each blank with a suitab

Fill in each blank with a suitable word given below.
at   glow   through   seeing   by   under   generate   reflecting   shaking
“When tbe stress of an earhquake hits the rock, it breaks chemical bonds... creating holes of positive electrica! cliarge. These hoies can flow vertically21the fauit to the suriace, niggering strong local electric fields that can22 light," according 0 Nature. The existence of these holes was proposed in 200323researcher Friedemann Freund, who wrote that " 24 normnal conditiorns these holes are dormant, but when they wake up during earthquakcs, the rocks begin to sparikle and25." The researchers sifed through many strange tales to arrive. 26 their final 65 reliable sightings, Nature reported. Among those: Of the Peruvian coast in August 2007, a fisherman reported the sky turning violet a few minutes before the sea began 27 . Near Ebingen, Germany, in November 1911, a woman reported 28 glows that moved along the ground “Iike snakes”as a quake began. Spreading the word about carthquake lights could help them to be used as possible earthquake warnings. In at least one case, lights have alerted people about an, impending quake, according to Nature: "Near L'Aquila, Italy, in Apil 2009, a man saw white flashes29 off his kitchen furniture in the carly hours of the morning and took his family outside30 safety." And two hours later, a huge earthquake rocked the region.
回答第（21）空
【正确答案】：through