他们无法解析您的请求，因为您试图将其发送到未加密的https端口(443).您可以尝试将其发送给http端口(80)，但是无论如何它们都会将您重定向到 https://coursera.org

They can't parse your request because you are trying to send it to https port (443) unencrypted. You can try to send it http port (80), but they will redirect you to https://coursera.org anyway.