Why are you so anxious? It isn’t your problem _____.
—— Have you seen___pen? I left it here this morning.—— Is it___black one? I think I saw it somewhere.
Many people agree that___knowledge of English is a must in___international trade today.
How beautifully she sings! I have never heard____.
If there were no examinations, we should have_____at school.
She is_____new comer to____chemistry but she has already made some important discoveries.