下列哪一项不是胚胎残余组织在颅内残留和异位生长形成的肿瘤（）
A.颅咽管瘤
B.脊索瘤
C.皮样囊肿
D.畸胎瘤
E.胶质瘤
参考答案：E
Steven is the ________ student in his class. He is good at all the lessons and ready to help others. [ ]
A. better
B. best
C. worse
D. worst
地基沉降的原因。
