男孩，5岁。咳嗽10d，近3d明显加重，尤以夜间为甚，阵发剧咳后有呕吐来诊。体检：体温 36.7℃，神志清，咽红，舌系带有溃疡，心脏无异常，两肺呼吸音粗，临床诊断为百日咳。请问百日咳患儿的抗生素应用至何时停药

A．咳嗽明显减轻，体温正常
B．阵发性痉挛性咳嗽消失
C．白细胞总数和淋巴细胞数恢复正常
D．鼻咽拭子细菌培养阴性
E．按规定剂量用药7～10d

  —Tony said he could fix my bicycle, but I really doubt it.

—_     __. He's good at that sort of thing.

A．Don't worry

B．Of course

C．A piece of cake

D．I couldn't agree more