We _____ walk in the park after supper, talking about all _____ we were interested in.

A．used to, what

B．were used to, what

C．used to, that

D．were used to, which

下列关于T细胞与B细胞的异同点的叙述正确的是[ ]

A．都是免疫细胞都能产生抗体

B．都是造血干细胞产生的，并都在骨髓中发育成熟

C．都能增殖分化产生记忆细胞

D．都能识别抗原都在细胞免疫过程中起作用