變故 [biàn gù]
unforeseen event
accident
mishap
misfortune
例句：1.生活中發(fā)生的重大變故往往是我們的第二次機(jī)會(huì).
We all have big changes in our lives that are more or less a second chance.
扁骨 [biǎn gǔ]
{生理} flat bone
os planum
例句：1.骨可根據(jù)形狀分類,有長骨、短骨、扁骨、不規(guī)則骨和含氣骨.
Bones may be classified according to their shape.There are long bones,short bones,flat bones,irregular bones and pneumatic bones.