Math Emperor, come on. On that determination of periodic function

A no. The function image of a is equivalent to inverting the right side of the Y axis and the left side of the Y axis of the image of sinx up and down, so the images are all non-negative in the interval from-π to π, and the second interval of continuous 2π images has never been found in the image of the whole function, so it is not.

B neither. Let's assume that he is, the period is t, and we take x=-T/2 and x=T/2. When x=-T/2, y=- 1+sin(-T/2) is non-positive, and when x=T/2, Y = 1. Even if the special case T=3π/2, the individual x and x+T are definitely not equal.

Whether C is still not, C is better to judge, and it is discussed directly in categories. When y=-sin 1, X < 0, when y=0, x> is at 0, and y=sin 1, assuming that there is a period t, the function values of x=-T/2 and x=T/2 are different.

In fact, the faster way is to draw directly, and you will know it at a glance.