Here is a question about this article: The city lies on approximately 200 deep canyons and hills separating its mesas, creating small pockets of natural open space scattered throughout the city and giving it a hilly geography. Traditionally, San Diegans have built their homes and businesses on the mesas, while leaving the urban canyons relatively wild. Thus, the canyons give parts of the city a segmented feel, creating gaps between otherwise proximate neighborhoods and contributing to a low-density, car-centered environment. The San Diego River runs through the middle of San Diego from east to west, creating a river valley which serves to divide the city into northern and southern segments. The river used to flow into San Diego Bay and its fresh water was the focus of the earliest Spanish explorers.[citation needed] Several reservoirs and Mission Trails Regional Park also lie between and separate developed areas of the city.
What is the answer to this question: What is created by the many canyons and hills throughout San Diego?
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So... small pockets of natural open space


Here is a question about this article: Asthma is clinically classified according to the frequency of symptoms, forced expiratory volume in one second (FEV1), and peak expiratory flow rate. Asthma may also be classified as atopic (extrinsic) or non-atopic (intrinsic), based on whether symptoms are precipitated by allergens (atopic) or not (non-atopic). While asthma is classified based on severity, at the moment there is no clear method for classifying different subgroups of asthma beyond this system. Finding ways to identify subgroups that respond well to different types of treatments is a current critical goal of asthma research.
What is the answer to this question: What  is asthma usually classified based on?
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So... severity


Here is a question about this article: Most of the Low Countries had come under the rule of the House of Burgundy and subsequently the House of Habsburg. In 1549 Holy Roman Emperor Charles V issued the Pragmatic Sanction, which further unified the Seventeen Provinces under his rule. Charles was succeeded by his son, King Philip II of Spain. In 1568 the Netherlands, led by William I of Orange, revolted against Philip II because of high taxes, persecution of Protestants by the government, and Philip's efforts to modernize and centralize the devolved-medieval government structures of the provinces. This was the start of the Eighty Years' War.
What is the answer to this question: Why did the people of the Netherlands rise up against Philip II?
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So...
high taxes, persecution of Protestants by the government, and Philip's efforts to modernize and centralize the devolved-medieval government structures of the provinces