When his headaches developed Nick became bad-tempered and even violent.尼克出现头痛时脾气就变得很差，甚至还会动粗。Larry began suffering severe headaches and violent mood swings.拉里开始出现严重的头痛和剧烈的情绪波动。It is necessary initially to classify the he...
Many nuclei have become shrunken and dark and have then undergone karorrhexis ( fragmentation ) and karyolysis ( dissolution ).许多细胞核发生了核浓缩,接着出现核碎裂和核溶解现象....
颊窝毒蛇的毒牙是长的空心管子.The fangs of pit vipers are long, hollow tubes.只有四分之一的蛇具有毒液和毒牙.Venom and fangs are found in only a quarter of all known snakes.在蛇的进化史上,毒牙的出现是新的进步.A more recent advance in the evolutionary story of snakes i...