第15题: [单项选择]外墙抹灰的总厚度一般不大于()。 A. 15mm B. 20mm C. 25mm D. 30mm 参考答案:B
第16题: [单项选择]Arctic explorers may catch colds when ______. A. they are working in the isolated arctic regions B. they are writing reports in terribly cold weather C. they are free from work in the isolated arctic regions D. they are coming into contact again with the outside world 参考答案:D 答案解析:推论题 根据第二段最后一句,北极探险者在与外界已感冒的人接触或收到来自外界的物品时易感冒,即受到病毒传染,D项符合文意。