军团菌病肺炎主要是由下列何种军团菌引起

A．米克戴德军团菌

B．嗜肺军团菌

C．费里军团菌

D．长滩军团菌

E．橡树岭军团菌

I ________a primary school student two years ago.

A．am

B．was

C．be

D．were