()是使不锈钢产生晶间腐蚀的最有害元素。
A.铬
B.镍
C.铌
D.碳
参考答案:D
—Why don’t you practise speaking and improve your spoken English?
— _____.[ ]
A. It doesn’t matter
B. That’s a good idea
C. Sorry, I forgot it
D. You’re welcome
A.3 B.4 C.5 D.6