英語六級攻克閱讀關鍵句229. Prices fluctuate, in response to harvests

229. Prices fluctuate, in response to harvests, natural disasters and political instability; and when they rise, it takes some time before new sources of supply become available.

譯文　價格由于收成、自然災害和政局的動蕩而波動；當價格上升時，得過一段時間后才會出現(xiàn)新的供應源。

點睛　本句的主干是Prices fluctuate...；it takes some time...。其中，in response to引導原因狀語；before引導時間狀語從句。

fluctuate意為“波動，變動”。本句中的in response to為固定短語，意為“作為對……的回應”。如：

He only shrugged his shoulders in response to the question. 他只是聳了聳肩，作為對問題的回答。

instability意為“不穩(wěn)定；不安定”。如：

The riot can be considered a symptom of political instability. 這次暴動可以看做政治上不穩(wěn)定的征兆。