Evidence has been found through years of study _____ children’s early sleeping problems are likely to continue when they grow up.

A．why

B．how

C．that

D．whether

肾细胞癌的临床病理特点有（）

A.主要症状是出血、贫血

B.早期即可发生血道转移

C.肾上、下极多见

D.多呈明显的浸润性生长，边界不清

E.癌组织间质少