Mass deaths of birds were not unheard of, but they normally happened unnoticed at sea or in rural areas away from towns. Many birds are weak and die in winter _______ food is scarce.
--- Look! Everything here is under construction. --- What’s the pretty small house that _______ for?
In our class there are 46 students, _______ half wear glasses.
Mr. Thomas is ______ a teacher to us. We look on him as our friend.
---Whose case is it? --- I’m not quite sure. But maybe it _______ Mr. White.
In order to by the education circle, he woks very hard.