perchlorocarbon是什么意思

用法例句

The contents of total N, total K and total P in earlier stage were higher than the contents in latter stage,so it needed fast fertilizer in earlier stage and its fertilizer absorbed reduced greatly in latter stage.

对1年生桔梗营养生长期农艺性状和N、P、K积累的动态进行了调查,结果表明:在本地区,桔梗营养生长盛期为8～9月;在生育初期体内全N,全P,全K含量高于后期,因此桔梗需施底肥,且后期吸肥量明显降低。