As is announced in the newspaper, the 20^th World Cup __________ in 2014 in Brazil between June and July.

A．is held

B．will be held

C．will hold

D．will be holding

A/A/O(A²/O)法中，第一个A段是指( )，其作用是( )，第二个A段是指( )，其作用是( )。

A．厌氧段，释磷，缺氧段，脱氮
B．缺氧段，释磷，厌氧段，脱氮
C．厌氧段，脱氮，缺氧段，释磷
D．缺氧段，脱氮，厌氧段，释磷