(v.) need /niːd/ → cần → I need your help. (n.) necessity /nəˈsesəti/ → sự cần thiết → Water is a basic necessity. (adj.) necessary /ˈnesəsəri/ → cần thiết → It is necessary to study. (adj.) unnecessary /ʌnˈnesəsəri/ → không cần thiết → That step is unnecessary. (adv.) necessarily /ˈnesəsərəli/ → nhất thiết → It does not necessarily mean success. (adv.) unnecessarily /ʌnˈnesəsərəli/ → không cần thiết → He worried unnecessarily.