GRE Text Completion: JiJing 1373-GRE填空机经1373题 - KC7Z7YVFUU9B59WJA

Gravitational waves – ripples in the geometry of space-time – are analogous to electromagnetic waves. The challenge in trying to observe these waves directly is that they are extremely weak. To make waves large enough to be (i)____________, the most (ii)____________ events in the universe are required: supernova explosions, the formation of black holes, or the collision of stars. Even so, the effects are (iii)____________. The geometry changes so little that a distance of several kilometers changes by less than the diameter of a proton. A. detectable B. obvious C. masked D. usable E. subtle F. disastrous G. explicable H. violent I. minuscule