Sometimes smiles ______ be false, hiding other feelings like anger, fear or worry.

I tried more than once to persuade the taxi driver to slow down, but he just __________ listen.

—How do you find the health club?—I          it. Everyone is saying its management is going from bad to worse.

--The man in a black suit _______ be our youth worker.--- I’m sure it _______ be him. I saw him in the laboratory building some minutes ago.

It’s difficult-------- me to learn English well.