A man steps on what seems like solid ground but discovers with horror that the ground is giving way beneath his feet. The man struggles （36）______ , but he is mercilessly （37) ______ . He cannot escape. Slowly he sinks deeper and deeper until at last he is gone, (38) ______ in the treacherous earth. The solid ground was solid only in (39) ______ . It was actually quicksand, which is a deep (40) ______ of fine sand mixed with water.
How is quicksand formed? Water pushes up from below the surface and is held by the sand. The (41) ______ of sand are forced apart by the water. They cannot hold any weight. The subsurface water may have come from a spring, a river, or a stream. Sometimes pools of water near beaches become filled with sand. When the soil under these pools does not allow for good drainage, the sand can become (42) ______ of quicksand.
Is it true that a man who steps into quicksand is (43) ______ to die? No, four men have fought their way from quicksand to firm land again. (44) _________________________________________________________ . Quick movements will make the sand yield temporarily, but then it rushes and settles solidly around the body.
(45) _________________________________________________________________ . When the weight of the sand his body has displaced equals his weight, he will stop sinking. (46) ___________________________________________________________________ .