A：$\left\{x|2k\pi \le x\le 2k\pi +\frac{\pi }{2},k\in Z\right\}$

B：$\left\{x|k\pi \le x\le k\pi +\frac{\pi }{2},k\in Z\right\}$

C：$\left\{x|k\pi \le x\le k\pi +\frac{\pi }{3},k\in Z\right\}$

D：$\left\{x|k\pi -\frac{\pi }{3}\le x\le k\pi +\frac{\pi }{3},k\in Z\right\}$