Gineering
熱工保護
??? 情景例句
What is it?
怎么回事
Nothing for nothing and very little for a half penny.
一分錢，一分貨。
it is extremely difficult to estimate the true value of the services which people perform for us.
但要估算別人為我們為所提供的服務的價值卻是極其困難的。