轧制工字钢时，最好选用（）作为原料。
A.矩形坯
B.异形坯
C.板坯
参考答案：B
They went there to visit _____ friends. [ ]
A. them
B. theirs
C. their
D. they
—Thank God! This school term is coming to an end!
—Yeah , after all that hard work , we all a holiday.
A．preserve
B．observe
C．reserve
D．deserve
