Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
What is the Date at memorial stadium • minneapolis, mn, and an Opponent of northwestern?

### Inputs:
table_name: table, columns: ['Date', 'Opponent', 'Site', 'Result', 'Attendance']

### Response:
SELECT Date FROM table WHERE Site = memorial stadium • minneapolis, mn AND Opponent = northwestern