（请用小学三年级的数学知识解答）---**Problem 1**
**Question Stem:**
把3、7、8、9填在适当的□里, 使下式的商最大。
**Mathematical Expression Description:**
A division problem represented by a long division symbol. There is one empty square box (□) representing the divisor, placed outside the symbol to the left. Inside the symbol, there are three adjacent empty square boxes (□□□) representing the three-digit dividend.
**Problem 2**
**Question Stem:**
把3、7、8、9填在适当的□里, 使下式的商最小。
**Mathematical Expression Description:**
A division problem represented by a long division symbol. There is one empty square box (□) representing the divisor, placed outside the symbol to the left. Inside the symbol, there are three adjacent empty square boxes (□□□) representing the three-digit dividend.