1. By the time Jane gets home his aunt ______ for London to attend a meeting.
A. will leave B. leaves
C. will have left D. mind
分析：C。时间状语从句中用一般现在时表示将来，by加将来时间与将来完成时连用。又如：
By May I will have got a new car. 到5月我将已买到一辆新汽车。
The old currency will have been phased out by 2020. 旧币分阶段至2020年将全部禁止流通。
2. On her next birthday, Ann ______ married for twenty years.
A. is B. has been
C. will be D. will have been
分析：D。表示到将来某时（her next birthday）为止势必会完成的情况，英语要用将来完成时，故选D。又如：
Don't worry. It's a storm in a teacup. Everyone will have forgotten about it by tomorrow. 别担心，这不过是茶杯里掀风浪，到明天大家就都把这事给忘了。
If they succeed on Europe, then they will have reshaped the political and economic map of the world. 如果他们在欧洲获得成功，他们将会改变世界政治和经济格局。
3. —I hear that Jason is planning to buy a car.
—I know. By next month, he _______ enough for a used one.
A. will have saved B. will be saving
C. has saved D. saves
分析：A。根据句中的by next month可知空格处应填将来时态，故可排除C和D；至于是选A还是B，则需根据句意来确定，由于前文已说“正准备买车”，说明存钱已经存够了，故不宜选B。句意为：“我听说詹森计划要买一辆车。”“我知道，到下个月，他积蓄的钱就够买一辆二手车了。”