胚胎在处于哪一期时受到照射，可造成器官畸形（）。

A.着床前

B.器官形成

C.胎儿

D.植入前

E.胚胎

We _____ estimate the spirit of the Shanghai Expo too much, which is sure to play an important role in our daily life.

A．may not

B．should not

C．must not

D．cannot