（1） 当跳到第十步时，电子跳蚤离原点的距离是多少？亮了几次红灯？

（2） 若要亮十次红灯，则电子跳蚤至少需要跳几次？此时，离原点的距离是多少？

There is an electronic flea hopping back and forth along a number line; every time it lands on a negative number, a red light flashes once, whilst it does not flash when it lands on zero or a positive number. It starts at the point representing the number −2 (marking one flash of the red light). In the first step, it jumps 1 unit to the left; in the second step, 2 units to the right; in the third step, 3 units to the left; in the fourth step, 4 units to the right; and so on.

(1) When it reaches the tenth step, how far is the electronic flea from the origin? How many times has the red light flashed?

(2) If the red light is to flash ten times, how many times at least must the electronic flea jump? At this point, how far is it from the origin?

（闵行期中2025）

A. 所有的有理数都能用数轴上的点表示              B. 符号不同的两个数互为相反数

C. 有理数分为正数和负数                                  D. 倒数等于本身的数是1、0、-1

Which of the following statements is correct? (   )

A. All rational numbers can be represented by points on a number line.     
B. Two numbers with different signs are opposite to each other.

C. Rational numbers are divided into positive and negative numbers.    
D. The numbers whose reciprocals are equal to themselves are 1, 0 and-1.