合同修改与书面确认的表达 — 国际贸易填空题

某出口公司致函买方，同意将销售确认书第 S-821 号项下的装运期由3月延至4月，其余条款不变。按照外贸函电惯例，函中应写明：We have received your letter of March 5 requesting an extension of the shipment date. As requested, we have amended the said Sales Confirmation to read "Shipment in April" ____ "Shipment in March", and all other terms and conditions ______ (保持不变). Please countersign the amended confirmation and return one copy ____ our file.