手工金属极氩弧焊有加填充焊丝和不加填充焊丝的两种方法，后者主要用于打底焊。（）
参考答案：对
She usually buys CDs her favourite singers. [ ]
A. by
B. on
C. with
D. and
化纤制针织或钩编女式防风衣
