Illegal immigration is when someone moves into a country without the necessary paperwork. For example for people from Mexico to come to the us they need a green card. If they don’t have a green card it’s considered illegal immigration.
Illegal immigration refers to the migration of people into a country in violation of the immigration laws of that country, or the continued residence without the legal right to live in that country. Illegal immigration tends to be financially upward, from poorer to richer countries
Because ‘Sarah and her sisters has gone’ doesn’t sound right, ‘Sarah and her sisters has been’ also sounds wrong and ‘Sarah and her sisters have been’ doesn’t really make sense
