跨越机器的过桥或走台,行走路面应当用()钢板。
参考答案:花纹
---Doing sports ___ good for our health.
--- Yes, so I do morning _____ every day.
A.is, exercise
B.is, exercises
C.are, exercise
D.are, exercises
在同一行或段落中,不能混合使用不同的标题级别。