They are still very cautious about ______ side effect the new medicine will bring about, although the experts have tried it on about 2,000 patients.
The lake is calm and clear, and one of the things that _____in the water is the famous tower.
The roommates have lived for three years and not once _____with each other.
My hometown, _____I spent my happy childhood, has changed a lot.
_____that the girl with an incurable disease would die soon, the boy decided to help her make her last days beautiful and meaningful.
Exploring _____space is exciting, yet dangerous. There is _____need for both robots and humans for space exploration.