计算器是解决数学问题的方便辅助工具。

A calculator is a handy ___aid for solving math problems.

一本好字典可以是学习新语言的有用辅助工具。

A good dictionary can be a useful ___aid in learning a new language.

互动软件是一种有效的教学辅助工具。

Interactive software is an effective teaching ___aid.