The public sign in the library means people ________ smoke there.
could
must
couldn’t
mustn’t
—I like playing Chinese chess best. What about you?— football is my favourite sport.
一Who do you think is _______ actor?一I think Zhao Benshan is.
All parents should _______ better with their children.
一Did they take any photos? 一______.
一______was your day off? 一Great!