The Shanghai Expo has had a major impact upon China. It is the first World Expo _________ in a developing country in the event’s 159-year history.

A．having been held

B．to hold

C．being held

D．to be held

急性髓性白血病中最常见的3种类型是：

A．M5、M3、M6

B．M6、MO、M7

C．MO、M1、M2

D．M2、M4、M1

E．M1、M2、M3