forward-travelling waves向前: forward; onward; ahead传播: disseminate; propagate; spre ...的: 4次方是 The fourth power of 2 i ...波: wave向后传播的波: backward-travelling waves下载手机词典可随时随地查词查翻译关注微信公众号：chachacidian，回复:向前传播的波，即可在微信中查询翻译
