Prodan
氟硅酸钠
🗣️ 情景例句
so the old one will be ready
这个旧的又可准备
It is lost labour to sow where there is no soil.
没有土壤，播种也是徒劳。
knowing that others will carry on what I can no longer do,
明白了有人会继续我的未竟事业，