已知: a n =lo g n+1 (n+2)(n∈ N * ) ,观察下列运算: a 1 ? a 2 =lo g 32 ?lo g 43 = lg3 lg2 ? lg4 lg3 =2 , a 1 ? a 2 ? a 3 ? a 4 ? a 5 ? a 6 =lo g 32 ?lo g 43 ?…?lo g 76 ?lo g 87 = lg3 lg2 ? lg4 lg3 ?…? lg7 lg6 ? lg8 lg7 =3 则当a 1 ?a 2 ?…?a k =2012时,自然数k为( )
【单选题】听力原文: This area is for authorized personnel only. You must have a special pass to enter the area. Passes may be obtained at the Security Office upon presentation of a valid driver's license. You must ...