Which sentence features a shift in tense?
a. she is breaking the plates she is carrying.
b. grammar has always been the secret to good writing.
c. he bought a car two weeks ago, and then he goes and buys a motorcycle last week!
d. the live broadcast will last until this evening, and then the station will return to its former programming.

Tungsten-filament lightbulb emits light based on the temperature of the filament. which phenomenon does this demonstrate?

28. a stone is projected at a cliff of height h with an initial speed of 42.0 mls directed at angle θ0 = 60.0° above the horizontal. the stone strikes at a, 5.50 s after launching. find (a) the height h of the cliff, (b) the speed of the stone just before impact at a, and (c) the maximum height h reached above the grou

One day, after pulling down your window shade, you notice that sunlight is passing through a pinhole in the shade and making a small patch of light on the far wall. you see that the patch of light seems to be a circular diffraction pattern. it appears that the central maximum is about 1 cm across and you estimate that the distance from the window shade to the wall is about 3 m. what is (a) the average wavelength of sunlight? (b) the diameter of the pinhole?