Birds have mammary glands

the class of turtle is

Lampreys belong to the phylum Chordata

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Lenses can be used to focus sunlight to a small point to burn paper or dry brush. A person demonstrates this using their own eyeglasses as the lenses. From this you can tell that

A nearsighted person requires glasses with lenses that are

A shaving mirror and a make-up mirror both magnify the image. Thus, these mirrors are ___________ mirrors.

When a wave reflects from a stationary boundary,

When a wave crosses from one medium into another in which the wave speed is lower, the frequency is unchanged. The wavelength

The period and the frequency of a sound wave are