①表示一個動作到將來某個時間為止已經(jīng)完成厂画，強調(diào)對將來那個時間產(chǎn)生的影響执解。
例：Pick me up at 8 o'clock,I will have had breakfast by then.
早上8點鐘你來接我,到時我已經(jīng)吃完早飯了.
②表示一個動作延續(xù)到將來某個時間的妖，并且有可能繼續(xù)延續(xù)下去抚芦。
例：The conference will have lasted a full week by the time it ends.
會議從開始到結(jié)束將持續(xù)整整一個星期帆赢。
