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

Q: Passage: Wings of bats and birds serve the same function. Look closely at the bones inside the wings. The differences show they developed from different ancestors. Answer: bones inside wings

A: Wings of bats and birds serve the same function. which body part should you study to understand ancestral differences?
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Q: Passage: and . The electric force is 39 orders of magnitudes bigger. Answer: 39

A: How many orders of magnitudes bigger is the electric force?
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Q: Passage: The most common two-lens telescope, like the simple microscope, uses two convex lenses and is shown in Figure 26.23(b). The object is so far away from the telescope that it is essentially at infinity compared with the focal lengths of the lenses ( d o ). The first image is thus produced at. Answer: convex

A:
The most common two-lens telescope, like the simple microscope, uses lenses of what shape?
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