向货币数据类型字段输入数据时，不必键入美元符号和______。
参考答案：千位分隔符
It was along the Mississippi River ____ Mark Twain spent much of his childhood.[ ]
A. how
B. which
C. that
D. where
紫薇白粉病的病原为______，寄主植物为紫薇树。
A．细菌
B．真菌
C．病毒
D．害虫
