It’s always difficult being in a foreign country, ___________if you can’t speak the language.
The two girls are so alike that strangers find ______ difficult to tell them apart.
He is busy now, otherwise he ______ go with you for a walk.
Having a trip abroad is certainly good for the old couple, but it remains _____ whether they will enjoy it.
---How long will you stay here? ---I don’t know. ________.
Since then the number of people taking driving lessons _______ 20%.