下列常见的现象中，一定发生化学变化的是[ ]
A.食物腐烂
B.纸张撕碎
C.冰雪融化
D.铁丝弯曲
答案：A
生态平衡依赖于生态系统的_________能力。
The girls in the photograph are twins, is my classmate in high school.
A．the taller of them.
B．the taller of whom.
C．the tallest of that
D．the tallest of who
