The PRC website (www.cpi.com.cn) is only in Chinese. Therefore, I use one of the browser translating tools, for example www.google.translate.com. I have it on my Google tool-bar, so I can activate it whenever needed. A word of warning, however, some of the translations do not make any sense, so it is necessary to use a different translator, like www.bing.com/translator/.
The Chungwa website, https://www.post.gov.tw/post/internet/U ... D=24020404 plugs you directly into an illustrated listing of past and future stamps, all in English.
The Hongkong Post website, www.hongkongpoststamps.hk/eng/whats_new/index.htm, is an English version easily read.
The Macau Post folks seem to change their website each year, requiring some searching around to plug into the new one. https://philately.ctt.gov.mo/default.aspx seems to work well for now. Note that you can select language of choice in the upper right.