countless

无数次

Used to emphasize that something has happened very many times.

用于强调某事发生了非常多次。

无数次

Used to describe an innumerable number of times something has happened.

用于强调次数非常多。

无数的实例

Used to describe an innumerable number of examples or occurrences.

用于强调大量的例子

无数的信件

Used to describe an innumerable number of letters (correspondence).

用于描述数不清的信件（书信）。