题目

   There are two basic ways to see growth: one as a product, the other as a process. People have generally viewed personal growth as an external (外在的) result or a product that can easily be identified and measured. The worker who gets a rise, the student whose grades improve, and the foreigner who learns a new language—all these examples of people who have measurable results to show for their efforts.      By contrast (对照), the process of personal growth is much more difficult to determine, since it is a journey and not the specific signposts or landmarks along the way. The p研究人员培育了一种称为“裸鼠”的实验动物，这种鼠缺少胸腺其免疫功能表现为A．B细胞仍能形成，参与细胞免疫B．仍具有体液免疫C．没有任何免疫能力D．机体仍能产生细胞免疫