spontaneity

他们在旅行时总是保持随性，这让旅程充满了惊喜。

Their ___spontaneity while traveling always makes the trip full of surprises.

她一时兴起买了张机票去海边度假，这就是她的即兴风格。

She bought a plane ticket to the beach on a whim—that's her ___spontaneity for you.