pref. out; outside

pref. 表示“外；在外；向外”，变体有ef-，e-。

ex-置于元音字母以及c, p, t等辅音字母前，如：exit（出口）；explode（爆炸）；expose（暴露）；export（出口）；express（表达）。

ef-置于f字母前，如：effect（影响）；effort（努力）。

e-置于其他辅音字母前，如：edit（编辑）；elect（选出）；erupt（爆发）；eraser（板擦）；event（事件）；evident（明显的）。

其他例词

ex-: excellent; except; exclaim; exclude; excuse; excursion; exhibit; exhibition; expand; expect; expectation; expedition; expense; expensive; experience; experiment; expert; explain; explanation; explicit; exploit; explore; explorer; explosion; expression; extension; escape

e-: editor; edition; educate; educator; elevator; emergency; evaluate; evidence