单项选择题
During the Ice Ages, man developed the use of tools, and this is a way of protecting himself against（）
A. conflicts B. hazards C. faults D. shortcomings
单项选择题 In architecture(建筑学) ,a vault(拱顶) is a proof or ceiling in the （） of an arch.
单项选择题 The doctor suggests that a person （） exercises every day if he wishes to be healthy.
单项选择题 I don't mind washing up but I hate to（）the beds for the guests.
