If you meet difficulties when you are striving for your life goal, please ______ and you will succeed sooner or later.
Carol said that the work would be well done by the end of October, ________ personally I wondered completely.
They boy said ________ couldn’t he work out the problem but his teacher didn’t know how to do it.
She will have to find some other work for she can’t ________ this loud noise any more.
— Why weren't you at the meeting? — I ________ for a long distance call from my sister in America.
We have done things we ought not to have done and ________ undone things we ought to have done.