The London Underground in England is one of the few networks that uses a four-rail system. The additional rail carries the electrical return that, on third rail and overhead networks, is provided by the running rails. On the London Underground, a top-contact third rail is beside the track, energized at +420v DC, and a top-contact fourth rail is located centrally between the running rails at 210v DC, which combine to provide a traction voltage of 630v DC. London Underground is now upgrading its fourth rail system to 750v DC with a positive conductor rail energised to +500v DC and a negative conductor rail energised to -250v DC. However, many older sections in tunnels are still energised to 630v DC. The same system was used for Milan's earliest underground line, Milan Metro's line 1, whose more recent lines use an overhead catenary or a third rail.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): On the London Underground, a bottom-contact rail is located where?
Ah, so.. unanswerable

In addition, France's education system includes many institutes of technology, embedded within most French universities. They are referred-to as institut universitaire de technologie (IUT). Instituts universitaires de technologie provide undergraduate technology curricula. 'Polytech institutes', embedded as a part of eleven French universities provide both undergraduate and graduate engineering curricula.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): What's the three-letter acronym for institut universitaire de technologie?
Ah, so.. IUT

Physically, database servers are dedicated computers that hold the actual databases and run only the DBMS and related software. Database servers are usually multiprocessor computers, with generous memory and RAID disk arrays used for stable storage. RAID is used for recovery of data if any of the disks fail. Hardware database accelerators, connected to one or more servers via a high-speed channel, are also used in large volume transaction processing environments. DBMSs are found at the heart of most database applications. DBMSs may be built around a custom multitasking kernel with built-in networking support, but modern DBMSs typically rely on a standard operating system to provide these functions. from databases before the inception of Structured Query Language (SQL). The data recovered was disparate, redundant and disorderly, since there was no proper method to fetch it and arrange it in a concrete structure.[citation needed]
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): What do most database applications contain?
Ah, so..
DBMSs