Crystals may be insulators, semiconductors, or conductors.晶体可以是绝缘体, 半导体, 或导体.Semiconductors containing such impurities are called p - type semiconductors.含有这类杂质的半导体叫做P型半导体.It is not possible to name any particular conduc...
体型大的生物由于行动慢, 不可能猎取到动物性食物.With very large organisms that are now relatively sluggish, animal food cannot be caught.素食者不吃任何动物性食物,易患维生素B12缺乏症.Vegans consume no animal products and are susceptible to vitamin B 12 deficiency....