Your massage therapist knows that your back muscles are tighter than the strings on a ukulele; your shrink knows that half your tension comes from stress.
你的按摩师知道你的背部肌肉比女高音尤克里里琴弦还紧；你的心理医生会说你的紧张有一半来自于压力。
2
The transformation of weld forming is the results of dual functions of arc shrink and surface tension change.