As we know, blood types A and B cannot receive AB, but AB may receive A or B. Type O can give to any other group; hence it is often called the _____ donor.
A.general
B.popular
C.universal
D. common
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Very few scientists _____ completely new answers to the world’s problems.
A) catch up with
B) come up with
C) keep up with
D) put up with
10. The socks were too small, and it was only by _____ them that he managed to get them on.
A.spreading
B. extending
C. lengthening
D. stretching
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