Highlight the description of a black hole.

From the outside, a black hole is invisible. But if it's invisible, then how can we know it's there?

—A Black Hole Is NOT a Hole,
Carolyn Cinami DeCristofano

What does the description help you understand?

why people want to search for black holes
why a black hole is invisible in space
why it is strange that we know black holes exist
why we know that black holes exist

For the word below, click on the drop-down arrows to select the root and its meaning. version

The story line remains the same. the kids live in what was then one of the remaining beachfront slums, down the coast from the expensive malibu area. the beach was ruled by surfers, but in the afternoon, when the waves died down, some of the surfers, or their younger brothers, fooled around on skateboards. one day, skip engblom, the shop owner, comes up with a key breakthrough, polyurethane wheels: "they grip." with the additional traction, the z-boys try skating the sides of the big, open drainage canal that runs through the area. then comes a brainstorm: because of a drought, the area's swimming pools were drained. the kids started "borrowing" pools when the owners weren't home, to skate the curved sides.” where did “the lords of dogtown” originally practice their tricks? a. the beach c. an open drainage canal b. empty pools d. none of these

The empire state building was a.constructed by one hundred workers. b.was first lit up by president roosevelt. c.has more than one hundred stories. d took several years to complete.