animals can't afford to be choosy about what they eat. 动物们也无权挑剔自己的饮食
and nothing can afford to waste any energy. 一点能量都不能浪费
but the dry season is so severe that the trees can't afford to loose the amount of water that would evaporate from their broad leaves, 在炎热干燥的季节 树木无法承受水分从叶子上的大量流失
Neither can afford a lapse in concentration. 必须全神贯注,不能失败