利用（）切割方法，可以实现在金属上加工沟槽。
A.碳弧气割
B.水再压缩等离子弧
C.等离子弧
D.空气等离子弧
参考答案：A
You can’t imagine _____ when they received these nice Christmas presents.
A．how they were excited
B．how excited they were
C．how excited were they
D．they were how excited
机械性肠梗阻的疼痛性质是
A．钝痛B．绞痛C．刀割样疼痛D．锐痛E．胀痛
