合金元素在钢中能使C曲线右移,临界冷却速度()(填“提高”或“降低”),从而提高钢的()。
The teacher said that light () faster than sound.
A. has traveled
B. traveled
C. had traveled
D. travels
为消除T12钢工件中的网状渗碳体,常采用()热处理工艺。
— What’s a reasonable tip to leave to the waitress?— (), I usually leave 20% of the dinner price.
A. Help yourself
B. It’s up to you
C. That’s the point
D. It’s a deal