"A sweet temper" is a figurative expression, but "sweet coffee" is not. "甜蜜的性情"是個比喻的說法,而"甜咖啡"則不是。
Its absorption by a molecule causes all sorts of subtle changes in the vibrational or rotational energy of the molecule. 一個分子能吸收紅外光引起分子中振動能量和旋轉能量的各種各樣的微小變化。