[经] reserve for expiration of patents

zhuān lì quán xiāo jiǎn zhǔn bèi ㄓㄨㄢ ㄌㄧˋ ㄑㄩㄢˊ ㄒㄧㄠ ㄐㄧㄢˇ ㄓㄨㄣˇ ㄅㄟˋ