Dear sir/madam can be used as a salutation if you don't know the recepient.
查看答案
Your name and your purpose should be includeded in the beginning of an email.
A. 对
B. 错
You should make your message as detailed as you can to make the recepient understand what you said.
A. 对
B. 错
You can end your email with some phrases like "yours sincerely".
A. 对
B. 错
下面哪种组态的电路输入电阻最小
A. 共源极
B.共漏极
C. 共栅极
微信支付 
支付宝支付