又是一封no opening，回复求助

thank you for your application as graduate student in my laboratory. Unfortunately, I could not consider your application to accept additional graduate students as I won' have open positions until the end of 2011. There are not good textbooks on non-thermal food preservation; the books "High Pressure Processing of foods", Eds. Doona and Feeherry, IFT Press 2007 and "Pulsed Electric Fields Technology for the Food Industry", edited by Raso and Heinz, Springer 2006 are probably a good start. regards 我上个月发信说想申请他的秋季入学研究生，但我现在想申请冬季了，恰好他说2011尾有opening，我该怎么跟教授说我想改变主意申冬季呢。。。。