问题补充：
All his time research on Chinese history, he has no time for outdoor activities.
A. devoted to do
B. devoted to doing
C. devoting to doing
D. is devoted to doing
答案：
A. devoted to do
(答案→)B. devoted to doing
C. devoting to doing
D. is devoted to doing
解析：考查独立主格结构。本句在两个部分之间缺少连词，说明逗号前面不是一个完整的句子，只是一个短语。All his time devoted to doing…相当于一个原因状语从句B Because all his time is devoted to doing…；句意：因为他所有的时间都花在了研究中国历史上，所以他没有时间参加户外活动。故B正确。
