Such an exchange is voluntarily undertaken by both parties .

这样的交换是由双方自愿进行的。

After a certain age , programmers rarely switch languages voluntarily .

过了一定的年龄，程序员很少再会主动的更换语言了。

That is , someone like parks could not act voluntarily while not fully conscious .

即像帕克斯这样的人在没有完全清醒时不可能自发地行动。

Within a week , the escort service voluntarily changed its number .

就在一周之内，那个公司就自动更改了电话号码。

Did tribes voluntarily delegate authority to a powerful ruler ?

部落会自愿将权力转交给强大的统治者吗？