[单项选择]That tragedy distressed me so much that I used to keep indoors and go out only ______necessity. A. within reach of B. for fear of C. by means of D. in case of
参考答案:D 答案解析:[解析] 根据上下文,本题空格处应该是说在需要的时候或万不得已的时候,D项 “in case of假如,万一”符合题意。其他三项“for fear of生怕,以免;within reach of在 可
第18题: [单项选择]What suggestion is offered for eating up the pie quickly() A. Looking sideways to see how fast your neighbor eats. B. Eating from the outside toward the middle. C. Swallowing the pie with water. D. Holding the pie in the right position. 参考答案:B 答案解析:
第29题: [单项选择]哪种是引起霍乱保护性免疫的基础( ) A. 细胞免疫 B. 循环抗体免疫 C. 肠道黏膜免疫 D. 抗菌免疫 E. 抗毒免疫 参考答案:C 答案解析:[解析] 人在感染霍乱弧菌后,小肠内有分泌型IgA形成,在肠黏膜与病菌之间形成一种免疫屏障,保护宿主肠黏膜免受霍乱弧菌及其肠毒素的侵袭。