用显微镜观察小鱼尾鳍内血液流动现象时,判断毛细血管的依据为:____ ,在实验过程中,为了使观察效果更好,应选取尾鳍含____ 少的活的小鱼.
Edward and William are brothers. There is uncommon similarity between two boys.
小明口算10道数学题用了1____.