无缝线路作业前,在维修地段应按需要备足道砟。
参考答案:对
如图,将三角形ABC沿水平方向向右平移到三角形DEF的位置,已知点A,D之间的距离为2,CE=4,则BF的长( )
A.4
B.6
C.8
D.10
Mr.Black is very happy because the clothes made in his factory have never been________.
A.popular
B.more popular
C.most popular
D.the most popular