Answer the question from the given passage. Your answer should be directly extracted from the passage, and it should be a single entity, name, or number, not a sentence.

Passage: The Doctor rarely travels alone and often brings one or more companions to share these adventures. His companions are usually humans, as he has found a fascination with planet Earth. He often finds events that pique his curiosity as he tries to prevent evil forces from harming innocent people or changing history, using only his ingenuity and minimal resources, such as his versatile sonic screwdriver. As a Time Lord, the Doctor has the ability to regenerate when his body is mortally damaged, taking on a new appearance and personality. The Doctor has gained numerous reoccurring enemies during his travels, including the Daleks, the Cybermen, and the Master, another renegade Time Lord. Question: How often does Doctor Who travel by himself?
rarely

Passage: Aristotle provided a philosophical discussion of the concept of a force as an integral part of Aristotelian cosmology. In Aristotle's view, the terrestrial sphere contained four elements that come to rest at different 'natural places' therein. Aristotle believed that motionless objects on Earth, those composed mostly of the elements earth and water, to be in their natural place on the ground and that they will stay that way if left alone. He distinguished between the innate tendency of objects to find their 'natural place' (e.g., for heavy bodies to fall), which led to 'natural motion', and unnatural or forced motion, which required continued application of a force. This theory, based on the everyday experience of how objects move, such as the constant application of a force needed to keep a cart moving, had conceptual trouble accounting for the behavior of projectiles, such as the flight of arrows. The place where the archer moves the projectile was at the start of the flight, and while the projectile sailed through the air, no discernible efficient cause acts on it. Aristotle was aware of this problem and proposed that the air displaced through the projectile's path carries the projectile to its target. This explanation demands a continuum like air for change of place in general. Question: Where did Aristotle believe the natural place for earth and water elements?
on the ground

Passage: The Far Eastern collections include more than 70,000 works of art from the countries of East Asia: China, Japan and Korea. The T. T. Tsui Gallery of Chinese art opened in 1991, displaying a representative collection of the V&As approximately 16,000 objects from China, dating from the 4th millennium BC to the present day. Though the majority of art works on display date from the Ming and Qing dynasties, there are exquisite examples of objects dating from the Tang dynasty and earlier periods. Notably, a metre-high bronze head of the Buddha dated to c.750 AD and one of the oldest items a 2,000-year-old jade horse head from a burial, other sculptures include life-size tomb guardians. Classic examples of Chinese manufacturing are displayed that include lacquer, silk, porcelain, jade and cloisonné enamel. Two large ancestor portraits of a husband and wife painted in watercolour on silk date from the 18th century. There is a unique Chinese lacquerware table, made in the imperial workshops during the reign of the Xuande Emperor in the Ming dynasty. Examples of clothing are also displayed. One of the largest objects is a bed from the mid-17th century. The work of contemporary Chinese designers is also displayed. Question: What is the name of the gallery devoted to Chinese art?
The T. T. Tsui Gallery