第17题: [单项选择]临床上出现可见黄疸时,总胆红素一般至少为()。 A. 17.1μmol/L B. 20.1μmol/L C. 251μmol/L D. 301μmol/L E. 341μmol/L 参考答案:E 答案解析:总胆红素的正常值为1.7~17.1μmol/L,17.1~34μmol/L为隐性黄疸,34~170μmol/L为轻度黄疸,170~340μmol/L为中度黄疸,340μmol/L为重度黄疸。故本题答案
第26题: [单项选择]The last half of the 19th century ______ the steady improvement in the means of travel. A. witnessed B. has witnessed C. is witnessed D. was witnessed 参考答案:A 答案解析:[分析] 时态用法
根据主语the last half of the nineteenth century可以判断时间为过去时,主语和谓语witness(亲眼目睹)之间是主动关系,因此A为答案