The word "da" (plain), "desu" (polite) is the copula verb. It corresponds approximately to the English "be", but often takes on other roles, including a marker for tense, when the verb is conjugated into its past form "datta" (plain), "deshita" (polite). This comes into use because only "i"-adjectives and verbs can carry tense in Japanese. Two additional common verbs are used to indicate existence ("there is") or, in some contexts, property: "aru" (negative "nai") and "iru" (negative "inai"), for inanimate and animate things, respectively. For example, "Neko ga iru" "There's a cat", "Ii kangae-ga nai" " haven't got a good idea".