第27题: [单项选择]分离人外周血淋巴细胞的分层液的比重为() A. 1.066 B. 1.077 C. 1.080 D. 1.090 E. 1.099 参考答案:B 答案解析:外周血中单个核细胞(淋巴细胞和单核细胞)的比重与红细胞、多核细胞、血小板不同,介于1.075~1.099之间,红细胞和粒细胞在1.092左右,血小板在1.030~1.035之间,因而利用比重介于1.0
第28题: [单项选择] Which of the following statements is NOT true A. The first cheerleader was a man named John Campbell. B. Cheerleaders’’ contests are only held at the state level. C. Before 1930 there were no women cheerleaders. D. The first cheerleading occurred in 1898. 参考答案:B 答案解析:从文中“Cheerleaders have their own contests every year at local,state and national levels.”可以得出B为不正确陈述。