某焊件的板厚δ为10mm、对接焊缝长10m，试求该焊件焊完后，其纵向收缩量ΔL为多少？
参考答案：
焊缝纵向收缩量为6mm。
Measures have been taken to prevent accidents, but much ______ for more improvement.
A．remains to be done
B．is remained to do
C．remains to do
D．is remained to be done
CRTSⅠ型双块式无砟轨道铺设，轨排的轨枕间距允许偏差为（）mm。
A、±5
B、±10
C、±15
