My friend , who ___on the International Olympic Committee all his life, is retiring next month.A served B.is serving C.had served D.has served
---How do you find my composition, Mr John? ---Good, ___too many spelling mistakes. You can’t imagine what great difficulty I had ___them.
He is only too ready to help others, seldom, _____, refusing them when they turn to him.
It is in their ability to speak ______ humans ______ from animals.
Tom, look at your shirt! It requires ________.
I am concerned ____ it that I can’t concentrate ____ my work because of headache.