(____)(1)A. first B.second C. three
(____)(2)A. classroom B.play C. playground
(____)(3)A. heavy B. high C. school
(____)(4)A. on B.in C. me
(____)(5)A.floor B. push C. swing
人体的呼出气体与吸入气体相比,氧气和二氧化碳含量的变化是
按要求填空:
(1)将80g质量分数为35%的浓盐酸,稀释成10%的稀盐酸,需加水的质量为 ____ g;
(2)简述在实验室如何稀释浓硫酸:____ .