選D
醫(yī)生盡最大努力來挽救患者的生命,但是失敗了.
前后兩個分句是轉(zhuǎn)折關(guān)系才比較合理.My cousin was so clever that he could___ the time at the age of four. A tell B talk C say D speak 好了采納！A可以翻譯成辨別tell the difference between辨別出兩者的差異其他選項沒有辨別的意思。