根据句意和所给中文写出句中所缺的单词。
1. —Where's Mr. Green? —He has gone to attend an ________(国际) meeting.
2. I write to my mother every week, ________ (主要) on Sundays.
3. The heavy work ________ (影响) his health, so he looked________ much older.
4. Do you know the saying, "A friend in need is a friend ________ (真正地).
5. It's important to ________ (教育) the young students.