On Oct 14,2011, Li Yantao, ___1__ seven-year-old pupil in the first experimental primary school of Weiyang district, Xi'an, capital of Shaanxi province, was confused when he was told he had to wear a
green scarf(绿领巾). "I don't think the green scarf is as good __2___ the red one, but I would be in
trouble with my teacher __3__ I did not wear it."The school decided to make children __4__ schoolwork and general behavior were not yet good enough wear green scarves instead __5__ the red scarf of the Chinese Young Pioneers. Parents whose children were given green scarves did not understand the
reason behind the school's measure and thought ___6___ was wrong to make some pupils wear green
scarves. Many pupils ___7___ wore green scarves took them off and put __8___ in their schoolbags
after they left the school grounds.In the end, Chen Hong, the school's principal, had to stop this practice
and said sorry to the parents.
时（T为交流的周期），原线圈中的电流瞬时值为0.03A．变压器的原、副线圈的匝数比为（ ）
：3