（）多见于6个月左右的婴儿，由于被套入的肠子血液供应受到阻碍会引起疼痛，时间过长可能发生坏死。
A.肠虫症
B.阑尾炎
C.肠套叠
D.腹泻
参考答案：C
Helen is 15 years old, and Joan is 15, too. So Helen is ____ Joan. [ ]
A. as big as
B. as older as
C. as old as
D. so old as
对任何辐射工作人员的剂量控制
