By adding the appropirate amounts of sugar, jams and jellies can made from any fruit.
In this sentences one of underlined wold is not good. It is obvious that using past particible after model is mistaken. But I am confused about amounts used in the sentence. Should -s be used after the word of amount? Thanks in advance.
My remark reffer to a simple rule that after modal such as should, would, can verb must be used base form. So it was just my typing error as in writing of appropriate. Thanks for your help Dozy.