In the end he entered his ideal school______ his hard work.     [ ]

A. because        

B. so              

C. because of          

D. as

有关恶性肿瘤的诊断方法中，正确性最高的是（）

A.症状与体征

B.有关化验检查

C.CT、MRI等检查

D.病理切片

E.肿瘤穿刺细胞学检查