供给函数
参考答案：
是指供给量与影响这一数量的诸因素之间关系的数学表达式。
选择正确的英文句子。
1. Kim喜欢玩娃娃。[ ]
A. Kim likes to play with toys.
B. Kim likes to play with his doll.
2. 我们喜欢做游戏，但是Kim喜欢玩玩具。[ ]
A. We like to play games, but Kim likes to play with toys.
B. We like to play with toys, but Kim likes to play games.
焊接低、中碳钢和低合金钢构件时，当其受力情况复杂时，宜选用（）。
A．与钢材强度相等的焊条
B．比钢材强度高一级的焊条
C．比钢材强度低一级的焊条
D．与钢材化学成分相同的焊条
