His careless driving ___ him his life last year.

A．spent

B．paid

C．took

D．cost.

对某一疾病进行筛检时，经筛检检出的病例有较长的临床前期，这些病例的生存期可能较长。为此，用这类病例来研究疾病的存活期时可能引起（）

A.混杂偏倚

B.领先时间偏倚

C.信息偏倚

D.病程长短偏倚

E.以上都不是