[ Grammar for TOEFL ]
Potassium has a valence of positive one because it usually loses one electron when _____ with other elements.
A. does it combine
B. it combines
C. in combining
D. combination
Select your answer:
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Do you think the kittens or the puppy (is, are) cuter?
A. are
B. is
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We _____________ the Empire State and Times Square.
A. have already seen
B. have just see
C. has yet saw
D. hasn’t still seen