付款条件的英文表达 — 国际贸易填空题

某出口公司与澳大利亚客户成交一批陶瓷餐具，合同金额为 USD 96,000.00。付款条款约定：买方须以电汇（T/T）方式预付合同金额的25%作为定金，其余75%货款采用不可撤销即期信用证（irrevocable sight L/C）支付，该信用证须在装运前15天开抵卖方。请将下列付款条款的英文表述补充完整： Payment: 25% of the contract value shall be paid in advance by T/T, and the remaining 75% shall be paid by ____ sight L/C, which shall reach the seller 15 days ____ shipment.