absorption tube keying system的用法和样例：
- They also poll key system files and executable files for unexpected changes.
- A device made of plexiglass is added between the gas absorption tube and gas flowmeter in the atmospheric sampler.
- Public announcement system is a key system in administrative law enforcement institution.
- The private key system is also called the single key system, in which the encryption process is the same as the decryption process.