B\u00e0i t\u1eadp tr\u1eafc nghi\u1ec7m H\u00ecnh h\u1ecdc 12 \u2013 Ch\u01b0\u01a1ng 3 \u2013 B\u00e0i 1: H\u1ec7 t\u1ecda \u0111\u1ed9 trong kh\u00f4ng gian (ph\u1ea7n 1)<\/a><\/blockquote><\/iframe>