Given a scientific passage and an answer, generate a question for the given answer.

Q: Passage: Equinox comes halfway between the two solstices. At equinoxes, the Sun's rays shine most directly at the Equator ( Figure below ). The daylight and nighttime hours are exactly equal on an equinox. The autumnal, or fall, equinox happens on September 22 or 23. The vernal, or spring, equinox happens March 21 or 22 in the Northern Hemisphere. Answer: equinox

A: What event occurs between the two solstices?
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Q: Passage: The pioneer species is soon replaced by other populations. Abiotic factors such as soil quality, water, and climate will determine the species that continue the process of succession. Mosses and grasses will be able to grow in the newly created soil. During early succession, plant species like grasses that grow and reproduce quickly will take over the landscape. Over time, these plants improve the soil and a few shrubs can begin to grow. Slowly, the shrubs are replaced by small trees. Small trees then are succeeded by larger trees. Since trees are more successful at competing for resources than shrubs and grasses, a forest may be the end result of primary succession. Answer: primary succession

A: What's the term for the gradual progression from simple plants to larger more complex ones in an area?
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Q: Passage: This bacterium, called Mycobacterium tuberculosis , causes the disease Tuberculosis (TB). These bacteria usually attack the lungs. If left untreated, the infection can be fatal. Many other illnesses, mild and severe, are also caused by certain types of bacteria. Answer: lungs

A:
What part of the body does the mycobacterium tuberculosis bacterium usually attack?
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