It remains to be seen ______ the newly formed committee’s policy can be put into practice.

_______ you call me to say you’re not attending my birthday party, I’ll see you at it．[ ]

John isn’t here right now. He ______ Mr. Black’s office. Perhaps he______ in several minutes.

As we all know, the number of Tibetan antelopes(藏羚羊) ________ becoming ___________.

Hardly ____ the airport when the plane took off.