如果考虑经济性，一般以采用（）为最合理。
A.弹簧钢
B.铍青铜
C.磷青铜
D.冷轧不锈钢
参考答案：A
一棵树上能结出不同品种的苹果，它采用的处理技术是（ ）
A．扦插
B．压条
C．嫁接
D．播种
—What they ?
—A new book. It's very interesting.[ ]
A. are; talking about
B. do; talk to
C. do; talking with
D. are; talking with
