Translate the following underlined sentences into Chinese. The past few centuries have witnessed balloon's expansion into various aspects of life. While small balloons are used as colorful decorations, scientists use weather balloons to collect meteorological data from the atmosphere. Balloons are even used by doctors to “inflate” the blood vessels of patients to aid in circulation.
医生甚至用气球来“扩张”病人血管，改善血液循环。 
