下列事件,与马可波罗没有关系的是()
A.17岁跟随父亲和叔叔前往中国
B.曾在元朝朝廷中任职
C.受指派到中国各地巡视
D.亲自撰写了《马可波罗行纪》一书
参考答案:D
-Look, an old man is in the middle of the street , it's too dangerous.
-Let's go and help him walk _______ the road. [ ]
A. through
B. along
C. across
D. over
在对流传热中流体质点有明显位移。