点头 nod one's head; nod点头同意 nod assent 点头打招呼 nod to sb. (as a greeting) 点头示意 signal by nodding 他已经点头了 He's already given the go-ahead. or He's already OK'd it.摇头 shake one's head 他摇了摇头表示反对。 He shook his head in disapproval. 他摇摇头,因为他的想法与此不同。 He shook his head, for he thought differently. 摇头表示否认. Shaking the head is a sign of negation