It's sometimes called "the silent killer" because it has no symptoms.

它有时也被称为“沉默杀手”，因为它没有任何症状。

youdao

Therefore high blood pressure is often called the silent killer.

因此，血压高，往往被称为无声杀手。

youdao

Expectation is the silent killer which murders millions of mushy and time tested relationships.

期待是一个沉默的杀手，谋杀了无数经过时间考验的人也人之间的关系。

youdao

Carbon monoxide is called the silent killer because people do not know it is in the air.

VOA: special.2010.02.02

"Hepatitis B is the silent killer because most people who are chronically infected may not be aware of the infection."

VOA: standard.2010.07.26

The gas is known as the silent killer because it cannot be seen or smelt.

BBC: Carbon monoxide detector

Known as the silent killer, ovarian cancer is the fifth leading cause of cancer death among women, killing 14, 600 annually.

FORBES: Leadership

Whether it's a deliberate attack, as with anthrax, or the outbreak of a slow and silent killer such as HIV, the Centers for Disease Control and Prevention is in the forefront of America's defense.

CNN: Recovery: Victims identified through DNA