feather alum造句

例句与造句

1. A pseudo alum is a double sulfate of the typical formula, where " A " is a divalent metal ion, such as cobalt ( wupatkiite ), manganese ( apjohnite ), magnesium ( pickingerite ) or iron ( halotrichite or feather alum ), and " B " is a trivalent metal ion.
2. It's difficult to find feather alum in a sentence. 用feather alum造句挺难的