题干
The conference was _______ fixed for the 10th, August, but later the unexpected landslide(泥石流) in Zhouqu in Gansu province, made us put it off.
A：normally
B：obviously
C：originally
D：presently
答案(点此获取答案解析）
C
U (l) 。取等量的E，分别在20℃、50℃测得E的转化率随时间变化的关系曲线(Y-t)如右图所示。