—It’s a little bit cold today, but you have sweat all over.

—Yes, I _______ around the city for almost three hours.

A．have hiked

B．was hiking

C．am hiking

D．have been hiking

下面关于B-淋巴细胞说法不正确的是（）。

A、通过抗体和抗原结合被吞噬细胞吞噬掉

B、产生抗体直接进到组织液中

C、被称为体液免疫

D、细胞本身有免疫功能