—Why do you look sad?—There are so many problems ________.

—Would you like to go to the cinema with me tonight?— I’d like to, but it remains ________ whether I can finish my homework in time.

Smiles around the world _____ be false, ______ other feelings like anger, fear or worry.

Tom always prefers _________on foot rather than _______ a bike.

The boy felt quite happy because he was closer now to ______ an answer of his own.