What is used to correct for both induced and permanent magnetism,and consequently must be readjusted with radical changes in latitude().
A. Flinders bar
B. Soft iron spheres
C. Fore-and-aft permanent magnets in their trays
D. Heeling magnet
在正常情况下,人体每天从食物中以蛋白质形式摄人的总氮量多于排出氮的量。
A. 正确
B. 错误
慢速跑健身法是指用较慢的跑速进行身体锻炼,每次慢跑时间控制在()分钟。
A. 20以下
B. 30~60
C. 20~30
D. 60以上