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

### Instruction:
When did the ship commissioned in November 1975 with a bow number of ps-18 launch?

### Inputs:
table_name: table, columns: ['Bow number', 'Ship name', 'Launched', 'Commissioned', 'Service']

### Response:
SELECT Launched FROM table WHERE Commissioned = november 1975 AND Bow number = ps-18