原电池的反应原理是 [ ]
A．储存电能
B．氧化还原反应
C．化合价变化
D．电能转化为化学能
答案：B
Many old buildings _____ in order to build the EXPO garden. [ ]
A. were put down
B. pulled down
C. were pulled down
D. put down
图形处理单元的英文缩写是（）
A.GPU
B.GDI
