A：{x|x∈R}

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

C：{x|x≠kπ，k∈Z}

D：$\left\{x|x\ne \frac{k\mathrm{\pi }}{2},\mathrm{k}\in \mathrm{Z}\right\}$