Twelve hours is the minimum, sixty hours the maximum.12小时为下限,60小时为上限.He walked two hundred and sixty miles in eight days.他在8天里走了260英里的路。I'm sixty-two. I feel sixty-two, neither more nor less.我现在62岁了，感觉自己也确实到这把年纪了。...
Thus only the metabolizable portions of a feedstuff can provide energy and essential nutrients.因此,只有饲料的可代谢部分可提供能量和必需的养分.Flours contain very small amounts of sugars which are metabolizable by yeast.面粉中一般都含有少量的糖,它们是酵母的代谢产生...