Why ___? It is not very serious.
A. to worry
B. worry
C. not worry
D. you are worried
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___ the road, don’t forget to look both ways.
As crossing
B. While you cross
C. While crossing
D. Cross
Chemistry is the science of substances ___ the science of energy.
A. and is physics
B. or is physics
C. and physics
D. or physics is
–Who broke the window?– ____.
A. Him
B. He
C. He broke
D. It is him
--You must obey every word of mine. ---____ I don’t?
A. How if
B. What if
C. Such as
D. Only if
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