lecture:e3_82_a4_e3_83_b3_e3_82_bf_e3_83_95_e3_82_a7_e3_83_bc_e3_82_b9_e3_83_87_e3_82_b6_e3_82_a4_e3_83_b3_e7_89_b9_e8_ab_96:e6_b3_a8_e6_84_8f_e4_ba_8b_e9_a0_85