这个系列的计算机非常快，但它们的后继产品将会更快。

This range of computers is very fast, but their ___successors will be even faster.

汽车的自然继任者在七十年代末首次被构想出来。

The natural ___successor of the car was first conceived in the late seventies.

这款新软件是先前版本的正式继任者，具有增强的安全功能。

The new software is the official ___successor to the previous version, with improved security features.