A. read a book
B. have lunch
C. go to school
D. have dinner
E. good morning
Please ____ ____! The baby is sleeping.
用化学用语填空
(1)2个铅原子____ ;
(2)3个氧气分子____ ;
(3)4个硫酸根离子____ ;
(4)氧化钙中钙元素显+2价 ____ .
小明去超市买三种商品.其中丙商品单价最高.如果购买3件甲商品、2件乙商品和1件丙商品,那么需要付费20元,如果购买4件甲商品,3件乙商品和2件丙商品,那么需要付费32元.