The old farmer, _____ the badly injured and burnt soldier, came out of the burning farmhouse, calling continuously for help.

A．supporting

B．having supported

C．being supported by

D．being supported

免疫细胞间的相互调节作用发生在免疫应答的哪一阶段（）

A.感应阶段

B.反应阶段

C.效应阶段

D.三个阶段都有

E.三个阶段都没有