焊接应力和焊接变形在焊接时是必然要产生的，但可以避免
参考答案：错
—This weekend we’re going to the Dancing Club. ______
—Yes, I’d like to.
A．Can I help you?
B．Would you like to join us?
C．What are you going to do?
D．What can I do for you?
接触电压触电是因为人体的手和脚同时触及漏电设备的外壳和地面（）。
