undetectable

例句：

1. 1. Thenew technology makes it impossible for us todetect any fraudulent activity.
   这项新技术使我们无法检测到任何欺诈行为。
2. 2. Thescientist was able to make the virus invisibleto the naked eye.
   科学家能够使这种病毒对肉眼不可见。
3. 3. Theinvisibility cloakis so effective that even themost observant detective could notdetect its presence.
   隐形斗篷如此有效，以至于最细心的侦探也无法发现它的存在。