2014 年 5 月 15 日，上海 EUDA 钟表贸易有限公司针对德国 BRIGTTE 进出口有限公司进行女士手表秋冬采购季的发盘。该发盘主要内容如下。 Dear Sir, We welcome your inquiry of May 10, 2014 and thank you for your interest in our products. With more than 20 years experience of manufacturing watch&clock, we have obtained a leading position in this trade and our sales have been increasing by about 30% each year. Therefore, we are quite confident that our cooperation will bring considerable profit to you. As request, we quote you our prices as following: Lady Watch M2001 @ US$ 7.22 DDP Hamburg for 1000pcs. Lyttelton 238 CTNS per 20 ’ container (min. Quantity) M2007 @ US$ 10.14 DDP Hamburg for 2000pcs M2009 @ US$ 5.51 DDP Hamburg for 5000pcs Packing: 20pcs per export carton. Insurance: To be covered for 110% of total invoice value against all risks as per C.I.C dated Jan. 1, 1981. Payment: By sight L/C for full contract value through a bank acceptable to the Seller. Shipment: On or before July 30, 2014. The above quotation is valid within ten days. You can find that our price representing the excellent quality of our products is really reasonable. We look forward to receiving your trial order soon. 该发盘是 5 月 15 日以特快专递寄出的给德国 BRIGTTE 公司， 5 月 16 日 EUDA 公司发现发盘中的付款条件不妥，希望改成 T/T 30% 定金加 70% 不可撤销信用证的方式，所以当天即用电传通知德国 BRIGTTE 公司宣告撤回该项发盘。问这样做是否可以？发盘是否可以撤回？根据是什么？