The twins,______at birth,do not know each other .
Many people volunteered to donate blood; however, the blood bank needs ________.
________ I admit that all these problems are difficult, I don’t agree that they can’t be solved.
Tom got to the hospital in time that day, ________the first bus.
--Why is the road so crowded? --The two underground lines ________.
--If you are admitted to a key university, ________ as a prize? --I’m looking forward to being paid for a journey to Tibet with my friends.