instruction:
This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.
question:
The avian circulatory system is driven by a four-chambered, myogenic heart contained in a fibrous pericardial sac. This pericardial sac is filled with a serous fluid for lubrication. The heart itself is divided into a right and left half, each with an atrium and ventricle. The atrium and ventricles of each side are separated by atrioventricular valves which prevent back flow from one chamber to the next during contraction. Being myogenic, the heart's pace is maintained by pacemaker cells found in the sinoatrial node, located on the right atrium. The sinoatrial node uses calcium to cause a depolarizing signal transduction pathway from the atrium through right and left atrioventricular bundle which communicates contraction to the ventricles. The avian heart also consists of muscular arches that are made up of thick bundles of muscular layers. Much like a mammalian heart, the avian heart is composed of endocardial, myocardial and epicardial layers. The atrium walls tend to be thinner than the ventricle walls, due to the intense ventricular contraction used to pump oxygenated blood throughout the body. Avian hearts are generally larger than mammalian hearts when compared to body mass. This adaptation allows more blood to be pumped to meet the high metabolic need associated with flight.
answer:
The avian circulatory system is driven by what?

question:
According to China daily. Fifteen years after the satellite system was launched, it is now generating $31.5 billion for major companies such as China Aerospace Science and Industry Corp, AutoNavi Holdings Ltd, and China North Industries Group Corp.
answer:
How long ago was the BeiDou Satellite System first launched?

question:
Ranked below the Three Councillors of State were the Nine Ministers, who each headed a specialized ministry. The Minister of Ceremonies was the chief official in charge of religious rites, rituals, prayers and the maintenance of ancestral temples and altars. The Minister of the Household was in charge of the emperor's security within the palace grounds, external imperial parks and wherever the emperor made an outing by chariot. The Minister of the Guards was responsible for securing and patrolling the walls, towers, and gates of the imperial palaces. The Minister Coachman was responsible for the maintenance of imperial stables, horses, carriages and coach-houses for the emperor and his palace attendants, as well as the supply of horses for the armed forces. The Minister of Justice was the chief official in charge of upholding, administering, and interpreting the law. The Minister Herald was the chief official in charge of receiving honored guests at the imperial court, such as nobles and foreign ambassadors. The Minister of the Imperial Clan oversaw the imperial court's interactions with the empire's nobility and extended imperial family, such as granting fiefs and titles. The Minister of Finance was the treasurer for the official bureaucracy and the armed forces who handled tax revenues and set standards for units of measurement. The Minister Steward served the emperor exclusively, providing him with entertainment and amusements, proper food and clothing, medicine and physical care, valuables and equipment.
answer:
Which individual had a duty to maintain the imperial stables?