氢是钢中危害性最大的气体，它在钢中的含量超过一定极限值时，会在锻后冷却过程中，在锻件内部产生白点和氢脆缺陷，使钢的塑性显著下降
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I have to finish my homework first_____ cleaning up the room.
A. because of
B. instead of
C. in front of
D. at the end of
Lu Han is_____an excellent actor _____ most teenagers like him.
A. such; that
B. so; that
C. too; to
D. not; but
He was _____crazy about rock music______he almost spent all his free time listening to it.
A. too; to
B. so; that
C. both; and
D. either;or
She is listening to music_____he is doing his homework.
A. after
B. before
C. while
D. whether
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