When you learn a foreign language, ________you must forget your own one.
I remember a ______ famous scientist said that we should believe in ourselves first of all.
We must not touch this switch under any ______.
I had written twice to Janet. But she didn't ______ my letters, so I decided to go there myself.
You've ______ a zero in this phone number, so you can't get through.
He did not regret saying what he did but felt that he ______ it differently.