Japanese speakers, when learning English, often drop the auxiliary verbs "be" and "do", incorrectly believing that "be" is a semantically empty copula equivalent to "です" and "だ".
Japanese also has two verbs corresponding to English "to be": aある and いる. They are not copulas but existential verbs. Aru is used for inanimate objects, including plants, whereas iru is used for animate things like people, animals, and robots, though there are exceptions to this generalization.
何で
このビールはおいしいです。
とは言うのに
このビールはおいしいだ
は言わないか、と言うのですけど…
よく分かんないなー。