相对于欧式认沽期权来说，美式认沽期权（）
A.价值较低
B.价值较高
C.有同样的价值
D.总是早一些实施
参考答案：B
— I ______ to your birthday party last Sunday!
— Unfortunately, you were on business. [ ]
A. had come
B. came
C. would come
D. would have come
土壤施肥的常用方法包括（）。
A.撒施
B.条施
C.根外追肥
D.浇施
E.环状施肥
