1、The voluntariness of their actions was evident in their willingness to help others without any expectation of reward.
他们行为中的自愿性在于他们无私地帮助他人而不期望任何回报。
2、The success of the charity event can be attributed to the voluntariness and dedication of the volunteers.
慈善活动的成功归功于志愿者们的自愿精神和奉献精神。