要实现文件切换所用的快捷键是（）
A、Ctrl+F6
B、Ctrl+F5
C、Alt+F6
D、Alt+F5
参考答案：A
Gong Li won an Oscar______ Best Actress _______ her role _______ this film.
A．of, for, in
B．for, of , of
C．for, for, in
D．of, of, in
简述天然传粉与自由传粉有何不同？
