21ST CENT. HISTORY
\twˈɛntifˈɜːst sˈɛnt], \twˈɛntifˈɜːst sˈɛnt], \t_w_ˈɛ_n_t_i_f_ˈɜː_s_t s_ˈɛ_n_t]\
Word of the day
Quinones
- Hydrocarbon rings which contain two moieties position. They can be substituted in any position except at the ketone groups.