碳14的半衰期约为5730年。

The ___half-life of carbon-14 is approximately 5,730 years.

这种止痛药的半衰期大约是4小时，意味着4小时后药效会减半。

The ___half-life of this painkiller is about 4 hours, meaning its effectiveness reduces by half after that time.

这款手机的热度半衰期只有三个月。

The ___half-life of this smartphone's popularity is just three months.