A：$\left\{\alpha |\alpha =2k\pi +\frac{\mathrm{\pi }}{4},k\in z\right\}$

B：$\left\{\alpha |\alpha =2k\pi -\frac{\mathrm{\pi }}{4},k\in z\right\}$

C：{α|α=kπ，k∈Z} 

D：$\left\{\alpha |\alpha =k\pi +\frac{\mathrm{\pi }}{2},k\in z\right\}$