instruction:
This task is about creating an unanswerable question based on a given passage. Construct a question that looks relevant to the given context but is unanswerable. Following are a few suggestions about how to create unanswerable questions:
(i) create questions which require satisfying a constraint that is not mentioned in the passage
(ii) create questions which require information beyond what is provided in the passage in order to answer
(iii) replace an existing entity, number, date mentioned in the passage with other entity, number, date and use it in the question
(iv) create a question which is answerable from the passage and then replace one or two words by their antonyms or insert/remove negation words to make it unanswerable.
question:
Passage: Other types of lossy compressors, such as the linear predictive coding (LPC) used with speech, are source-based coders. These coders use a model of the sound's generator (such as the human vocal tract with LPC) to whiten the audio signal (i.e., flatten its spectrum) before quantization. LPC may be thought of as a basic perceptual coding technique: reconstruction of an audio signal using a linear predictor shapes the coder's quantization noise into the spectrum of the target signal, partially masking it.
answer:
What is thought of as a basic signal coding technique?


question:
Passage: BYU has been considered by some Latter-day Saints, as well as some university and church leaders, to be "The Lord's university". This phrase is used in reference to the school's mission as an "ambassador" to the world for the LDS Church and thus, for Jesus Christ. In the past, some students and faculty have expressed dissatisfaction with this nickname, stating that it gives students the idea that university authorities are always divinely inspired and never to be contradicted. Leaders of the school, however, acknowledge that the nickname represents more a goal that the university strives for and not its current state of being. Leaders encourage students and faculty to help fulfill the goal by following the teachings of their religion, adhering to the school's honor code, and serving others with the knowledge they gain while attending.
answer:
What is BUY considered to be by some?


question:
Passage: A commutator is a mechanism used to switch the input of most DC machines and certain AC machines consisting of slip ring segments insulated from each other and from the electric motor's shaft. The motor's armature current is supplied through the stationary brushes in contact with the revolving commutator, which causes required current reversal and applies power to the machine in an optimal manner as the rotor rotates from pole to pole. In absence of such current reversal, the motor would brake to a stop. In light of significant advances in the past few decades due to improved technologies in electronic controller, sensorless control, induction motor, and permanent magnet motor fields, electromechanically commutated motors are increasingly being displaced by externally commutated induction and permanent-magnet motors.
answer:

 What would a rotor do with current reversal?