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【单选题】Color is very important to most animals for it helps them to get along in the world. Color (21) to make an animal difficult for its enemies to (22) . Many animals match their (23) so well that as lon...
A.
Even if
B.
Unless
C.
However
D.
As long as
【单选题】除哪项外，有下列情况者均不能献血（）。
A.
性病、麻风病和艾滋病患者及艾滋病病毒感染者
B.
同性恋者、多个性伴侣者
C.
有吸毒史者
D.
阑尾切除手术后
E.
各种恶性肿瘤及影响健康的良性肿瘤患者