Safety in schools has been of great concern because of frequent reports about accidents ________ students got injured or killed while in school.[ ]

Tracy doesn’t know many people here. – ______, we have stayed here for onlytwo days.

Today I’ll go to the zoo with my parents. —_____________

become addicted to online games, ______about what is more important.

Our enemy bills have been increasing steadilythese costs，our telephone costs have doubled over the past six months