397.Experts have been warning _____ of the health risks caused by passive smoking.
A.at a time
B.at one time
C.for some time
D.for the time
398.She devoted herself _____ of the health and it earned her a good reputation in her field.
A.strongly
B.extremely
C.entirely
D.freely
397.答案是C;此题考查与time相关的介词短语。At a time 一次；at one time 曾经；for some time 长达一段时间。由have been warning可知选C。
398.答案是C；strongly 强烈地；extremely 极端地；entirely 完全地；freely 自由地。句意:她全身心地投入研究工作，这使她在其领域中赢得了良好的声誉。
