Which of the following is NOT a Mars rover?
A) Spirit
B) Sojourner
C) Curiosity
D) Viking
Question 2
According to general relativity, a black hole is
A) an object that cannot be seen.
B) a hole in the observable universe.
C) a place where light travels slower than the normal speed of light.
D) a place where light travels faster than the normal speed of light.
E) a place where there is no gravity.