上一讲简单谈了左手的“三换技巧”，即换弦、换指、换把。如同右手的换弓、换弦技巧的重要性一样，“三换”技巧是左手的基础。本讲着重谈谈揉弦，此外，再简单谈谈保留指、预备指、和弦、双音、泛音、颤青、投弦、半音滑奏等左手技巧。一、揉弦揉弦是弦乐器特有的技巧，不管 The last talk briefly about the left hand “three for skills”, that change the string, change fingers, change to. As with the right hand for bow, the same as the importance of changing skills, “three for” technique is the basis of the left hand. This talk focuses on rubbing strings, in addition, briefly talk about the retention finger, preparation finger, chord, dual tone, overtone, trembling, cast string, semitone and other left-handed skills. First, rubbing string is a string instrument unique skills, no matter