长途飞行后，医生警告他可能有血栓栓塞的风险。

After the long flight, the doctor warned him about the risk of ___embolism.

为了保持宗教节日与季节同步，教会使用了闰日来调整历法。

To keep religious festivals in sync with the seasons, the church used an ___embolism to adjust the calendar.