结构推理 请对4776号信用证作如下修改：
   (1) 金额增加人民币506元。
   (2) 每箱装12打改为每箱装20打。
【正确答案】Please amend L/C No． 4776 as follows:
   (1) Amount is to be increased by RMB 506．
   (2) The words "12 dozen per carton" are to be replaced by "20 dozen per carton"．
【答案解析】