一封闭体系，经历一系列变化又回到了初始状态，则下列关系正确的是（）
A. Q =
B. 0，W ≠ 0，DU = 0，DG = 0
C. B．Q =
D. -W，DU = Q+W，DH = 0
E. C．Q ≠ 0，W = 0，DU = 0，DH = Q
F. D．Q ≠ -W，DU = Q+W，DH = Q
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Which of the following techniques is similar to the math equation, “x = y”（）
A. Renaming the subject
B. Giving antonyms
C. Giving synonyms
Defining with a negative
Where should we place the definition in a paragraph（）
A. It usually appears in the topic sentence
B. It usually appears in the ending sentence
C. It is usually put in the middle of the paragraph
D. It usually appears amongst supporting details
Freddy was such a troublemaker that the teacher put his desk in a far corner to isolate him from the other students（）
A. to protect
B. to separate
C. to recognize
D. to prohibit
Selina did extensive research for her paper — it took her several weeks（）
A. done quickly
B. risky
C. large in amount
D. disgusting
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