numerous

在线课程曾经不常见，现在却有很多。

Online courses, once uncommon, are now ___numerous.

这类商店曾经很稀有，现在却很多。

Shops of this type, once rare, are now ___numerous.

该地区栖息着许多稀有鸟类。

The region is home to ___numerous rare bird species.