手工锯切铜元，中低碳钢宜选用（）锯条，锯切硬钢，管子宜选用（）锯条。
参考答案：粗齿，细齿.
We are ______when we hear the _______news -we don’t have classes tomorrow.
A．exciting; excited
B．excited, excited
C．excited; exciting
D．exciting; exciting
