Hardpan
n. 硬質地層, 未開墾的硬地, 粘土層
??? 情景例句
I've been wrestling
我一直左思右想
You should be punctual for appointments.
你應該準時赴約。
Yet a great many processes depending on such research are sought for with complete secrecy until the stage at which patents can be taken out.
然而，依賴這種研究的很多工藝程序是在完全保密的情況下進行的，直到可以取得專利權的階段為止。