Which is most likely the first invention that changed society so much?
a. the airplane
b. the steam engine
c. the car
d. the train

What kind of bond is created by the attraction between atomic particles of opposite charge? ionic bond hydrogen bond covalent bond nuclear bond

Which of the following is not associated with invasive species?

Which of the following correctly matches an immune system cell with the defense it produces? a. b cells release cytotoxins. b. t cells release cytotoxins. c. b cells absorb antibodies. d. t cells absorb antibodies.