Now, if we just look at the QRS complex, which normally lasts less than 100 milliseconds or 2-and-a-half little boxes, it's usually made up of three smaller waves, also called deflections.

好，如果我们只看QRS复合波，它正常持续<100毫秒，或占2.5个小格，通常由三个小波组成，也叫做偏转波。