English to Chinese Science Linguistics

The four-eye principle requires that a single operation be performed by two different people. In addition to protecting from honest mistakes, this is to ensure that one person cannot go rogue and do something disastrous alone. One of the most famous systems incorporating the four-eye principle are many nuclear weapon delivery systems, which require two people turn keys in locks that are far apart at the same time. It is important that the two actions cannot be done one after the other, because then one person could do the first action and then the second by him or herself.