原发性肠套叠有以下特点
A.随着年龄增长发病率降低
B.有明显病因
C.常见于2岁以下婴儿
D.套叠段无明显的器质性因素
E.男孩是女孩的2~3倍
参考答案:A,C,D,E
The children must ______. [ ]
A. take care
B. taken care of
C. be looked
D. be looked after
瓦当