35. She couldn’t have answered the question if she ________ a few books on world history.                                                        

A．hadn’t read

B．hasn’t read

C．wouldn’t read

D．didn’t read

2岁男孩，突发性腹痛，大便带血，腹部可触及包块，包块处探及多层强弱回声团，呈"同心圆征"，最可能诊断是（）

A.肠套叠

B.肠扭转

C.小肠肿瘤

D.急性阑尾炎

E.坏死性小肠炎