He tried to deal with the increasing burden of his work,but he finally _____and had to take a complete

rest.   [ ]

A. broke off      

B. broke away        

C. broke out           

 D. broke down

婴幼儿最常见的肾肿瘤是（）

A.肾细胞癌

B.肾盂 * * 状瘤

C.肾血管平滑肌脂肪瘤

D.肾胚胎瘤

E.成神经细胞瘤