下列哪项不属于隐蔽抗原（）
A.精子
B.眼内容物
C.神经髓鞘磷脂碱性蛋白
D.细胞外抗原的自身抗体
E.以上答案全正确
参考答案：D
_____ to his experiment in the lab, the idea for the new plan came to his mind. [ ]
A. While devoting
B. While devoting himself
C. While he was devoted
D. While devoted
（）是使两个被观察物体成像在一个视野内进行比较研究的重要工具。
