Choose the correct answer.

A _______ of a disk-shaped object in the sky started to appear in local newspapers.

Choose the correct answer.

Alice _______ the accident when she was catching the bus.

Choose the correct answer.

What _______ when I called?

Choose the correct answer.

The prerequisite condition for a/an _______ planet is water supplies, appropriate temperatures and breathable air.

Choose the correct answer.

The scientists believe that there might be some planets to _______ human life.

Choose the correct answer.

What were you doing when you _______ the strange sound?

Choose the correct definition.

Researchers use this large spacecraft as a place to live and work in space.

Choose the correct answer.

The _______ can fall below zero degrees Celsius in winter.