It might be that the two base-pair system is the best.

ECONOMIST: A new kind of DNA

The system uses a pair of security officers.

CNN: Airport security bares all, or does it?

Hybrids need to be equipped with larger battery packs, smaller and more fuel-efficient engines and a "two-mode system" that uses a pair of electric motors that propel the car at lower speeds.

FORBES: Cleaner Cars

The pair were challenged over how the system was different if the family still had the final say.

BBC: Health and Social Care Committee

The system of polls and computer rankings aims to pair the nation's top two teams in the season's final game.

WSJ: BCS Championship 2012, LSU-Alabama: Should Voters Put the Tigers First for a Close Loss?

Mom and dad know that the rules are making it almost impossible for their daughter to receive a pair of lungs through the transplant system.

CNN: SHARE THIS

Such sum is divided equally between all the people involved in the production system, which on the case of the pair of jeans takes about seven individuals.

FORBES: Zara Accused Of Alleged 'Slave Labor' In Brazil

Ten days later, the pair's own crowd-funding system was up.

CNN: Lockitron: The app that unlocked crowd-funding success

Nowadays we're spoiled with options in the Bluetooth speaker market, and many of the high-end ones -- especially those from Soundfreaq and Nokia -- even feature dual-system streaming (DSS) that lets one speaker pair with another to enable true stereo playback.

ENGADGET

The pulsar and white dwarf pair emit gravitational waves and the binary star system gradually loses energy.

WSJ: Einstein Proved Right on Gravity��Again

This would require a pair of red dwarfs to encounter the solar system and perform an elaborate gravitational dance with it for a few thousand years.

ECONOMIST: To the ends of the earth