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

### Instruction:
When did the duchess who became duchess on 7/8 April 1766 cease to be duchess?

### Inputs:
table_name: table, columns: ['Name', 'Birth', 'Marriage', 'Became Duchess', 'Ceased to be Duchess', 'Death', 'Spouse']

### Response:
SELECT Ceased to be Duchess FROM table WHERE Became Duchess = 7/8 april 1766