16. For each empty space (1-6) choose the correct answer (A, B, C or D).
An earthquake (1) _____ when there are sudden movements in Earth’s crust that make the ground shake. Most earthquakes are small, and we (2) _____ them, but during large earthquakes, rocks (3)_____. The land may split apart along a crack in the crust (4) _____ a fault line. Some large fault lines (5) _____ above places where (6) _____ plates meet.

1 happened / happen / happens / has happened
2 didn’t notice / don’t notice / not notice / not noticed
3 are trembling / tremble / trembled / trembling
4 calls / call / called / were called
5 are lying / lay / lie / lying
6 Earth’s / Earth / Earths / Earth’