Original sentence: Another example is reading natural language instructions on how to reply, with the inclusion of a special string or pass-code in the reply.In early systems, clicking on the link was sufficient to respond to the challenge, or sending any reply to the message.Other Turing Test approaches include a problem, or answering a question about the text or the recipient.Some C/R systems allow the user to "whitelist" mailing lists to which they subscribe -- instructing the C/R software not to challenge their messages
Edited sentence: Another example is simply reading natural language instructions on how to reply, with the inclusion of a special string or pass-code in the reply.In early systems, simply clicking on the link was sufficient to respond to the challenge, or simply sending any reply to the message.Other Turing Test approaches include a simple problem, or answering a simple question about the text or the recipient.Some C/R systems allow the user to simply "whitelist" mailing lists to which they subscribe -- instructing the C/R software not to challenge their messages