Senior one math contest, senior one. Multiple-choice questions (5 points for each question, ***50 points) Only one of the following four conclusions is correct. Please fill in the English letters indicating the correct answer in the brackets after each question. Any positive odd power of 1. number A is equal to the reciprocal of A, then () A.B.C.D has no such value. 2. As shown in the figure, there are six points on the number axis, and the integer closest to the number represented by point C is () A. B. 0 C. 1 D. 2 (adapted from the topic provided by Wang Yuanzheng of Shekou Middle School in Nanshan District, Shenzhen). 3. Zu Chongzhi, a great mathematician in ancient China, calculated the pi as 3. 14 15926 and quite accurately. 5927, and take it as the density rate and reduction rate, then () A.B.C.D.4 Given that X and Y satisfy, then the value of the algebraic expression is () A.4B.3C.2D. 1.5. The sum of two positive integers is 60, and their least common multiple is 273. Then their product is () a.273b.819c.1911d.3549 6. Enclose an equilateral triangle with a line one meter long, and measure the area of this equilateral triangle as b square meters. Now let's take any point P in this equilateral triangle, and the sum of the distances from the point P to the three sides of the equilateral triangle is () m A.B.C.D.7 If we assume that be is the largest prime number not greater than A, then the result of the expression.