撒贝宁在戛纳大会的发言中用英语时，他的名字通常被读作"Sa Beining"。
这是因为"撒贝宁"在中文中的发音与英文音标并不完全对应。
"撒"发音类似于英文单词"sad"中的"sa"音，"贝"发音则类似于英文单词"bay"中的"be"音，"宁"读作英语单词"ning"中的"ning"音。
所以，根据这个规则，撒贝宁在戛纳怎么读的英语发音就是"Sa Beining"。
It is important to keep in mind that the English pronunciation of Chinese names may not always perfectly match the original language. Different languages have their own phonetic systems, and certain sounds in one language may not exist in another. In the case of Sa Beining, the pronunciation in English is a close approximation of the original Chinese name.