Nick is looking for another job because he feels that nothing he does____ his boss.

In view of all sorts of rumors and guesses, experts carried out some careful and scientific research and         the possibility of a second earthquake in this area.

A good idea _________   to  him, and he knew _______ to do next.

When she heard the good news, there appeared a ___ smile on her face.

Noone has _____ been able to trace the author of the poem.