—What are you busy with?—The conference in our city next week.
The earlier settlers learned to farm the land through ______ and error.
The moment she heard of the news that her son was involved in the crime, she ______ pale.
I didn't see you at the meeting. If you ______ , you would have met my brother.
Don't use words and expressions or phrases ______ only to people with specific knowledge.
Emergency line operators must always ______ calm.