这种植物需要肥沃的土壤才能生长良好。

This plant needs rich ___soil to grow well.

孩子们在泥地里玩耍，把裤子弄脏了。

The kids played in the mud and ___soiled their pants.

他游历了许多国家，最终选择在美国定居。

He traveled to many ___countries before finally settling in the United States.