A group of scientists at Bristol University, led by senior lecturer Anthony Croxford, discovered that ________________________________________________________.
布里斯托大学一群科学家在安东尼·柯瑞福的率领下发现，__________________________________。
“It lets you see smaller cracks, closed cracks, cracks that, so when I say closed cracks, imagine if you have a crack in a piece of metal, it could be a bit open like that, it could have a gap in between it. If you have a gap in between it, you get reflections off the edge of it, but you don't really know how big it is," said Croxford.
“这样就能看到很小的裂纹和闭合裂纹，我说到闭合裂纹，想象下一段金属上有个裂纹，其小裂口像这样，其中有空隙。如果之间有空袭，那么在边缘上就会有回音，但并不知道这个空隙究竟有多大。”
