Do you know ( that/ when/ if) the class starts?
when
Can you tell me ( that/ what / if) I should do now?
what
I didn’t know ( that/ when/ if) John is her boyfriend.
that / if
It is a fact ( that / what / whether) the sun rises in the east.
that
Sara wants to know ( that/ what / wether) you guys speak other languages.
whether
We all know ( that / how / if) regular exercise is good for us.
that
We are not sure ( that / when / if) the swimming pool is open or not tomorrow.
if
( That/ Whether/ Why) the show is a great success is true.
That
We are surprised ( that/ if / when) they’re getting married soon.
that
We wonder ( that / why / if) Anna didn’t come.
why