钢轨铝热焊中，降低低熔点物质的含量，提高（）的含量可改善型砂的耐热性能。
A.二氧化硅
B.水
C.碳粉
D.水玻璃
参考答案：A
关于颈静脉的检查，错误的是（）
A.颈静脉怒张可见于心包积液
B.正常人立位或坐位时颈外静脉常不显露
C.颈静脉怒张一般不会见于右心衰竭
D.若取30°~45°的半卧位时，颈静脉充盈度超过正常水平，称为颈静脉怒张
E.正常人平卧时稍见充盈，充盈的水平仅限于锁骨上缘至下颌角距离的下2/3以内
A senior firefighter said it was _____ that the fire, which broke out at midnight, was caused by
someone on purpose. [ ]
A. possibly
B. likely
C. probably
D. obviously
