选D
医生尽最大努力来挽救患者的生命,但是失败了.
前后两个分句是转折关系才比较合理.My cousin was so clever that he could___ the time at the age of four. A tell B talk C say D speak 好了采纳！A可以翻译成辨别tell the difference between辨别出两者的差异其他选项没有辨别的意思。