【单选题】When I saw my teacher nodding _______ to me, I calmed down and went on with my performance.
【简答题】水稻根属 ______ ,有 ______ 和 _______ 两种。
【单选题】When I saw mum nod _______ to me, I calmed down and went on with my acting.
【单选题】The price ________, but I doubt wheth er it will remain so. [ ]