underground
Definition
Beneath the surface of the earth; also refers to something hidden or secret.
中文 在地表以下；也指隐藏或秘密的事物。
Example
"The subway system runs through a network of underground tunnels."
Beneath the surface of the earth; also refers to something hidden or secret.
中文 在地表以下；也指隐藏或秘密的事物。
"The subway system runs through a network of underground tunnels."