ocean : _______ : desert : oasis leak : plumber : _______ : plasterer aquanaut : _______ : astronaut : space oaf : genius : ordinary : _______

The answers to your questions involve finding the relationship between the pairs.

1. ocean : island : desert : oasis

An island is a landform surrounded by water in an ocean, similar to how an oasis is a fertile area in a desert.

2. leak : plumber : crack : plasterer

A plumber fixes leaks, just as a plasterer deals with cracks.

3. aquanaut : submarine : astronaut : space

An aquanaut explores underwater (often using a submarine), just like an astronaut explores outer space.

4. oaf : genius : ordinary : exceptional**

An oaf is a term for someone lacking intelligence, while a genius is exceptionally smart; therefore, an ordinary person is less than exceptional.

Each answer fits the structure of relating two terms based on their functions or characteristics within a specific context. Let me know if you need further clarification on any of these!