题目

Bill's birthday is on the (six) day of this month. 答案：【1】sixth 诗句“春蚕到死丝方尽，蜡烛成灰泪始干”中“丝”和“泪”分别指 [　　] A． 纤维素、油脂 B． 蛋白质、烃类 C． 淀粉、油脂 D． 蛋白质、硬化油