A:降低
B:不变
C:升高
D:无法确定
—I don't think so. The key to his good grades is his hard work, not good luck.
把5盏电灯并排安在台子上,用〇表示点亮的电灯,用●表示关掉的电灯.〇和●按一定的顺序排列,可以表示一定的数值,如图:
在鸡卵中,真正属于卵细胞的结构是