解釋：
onlooker 英[?nl?k?(r)] 美[?ɑ:nl?k?(r)]
n. 旁觀者，目擊者; 觀眾（等於spectator）;
[例句]A handful of onlookers stand in the field watching.
少數幾個旁觀者站在現場觀看。
bystander 英[?ba?st?nd?(r)] 美[?ba?st?nd?]
n. 旁觀者; 局外人; 看熱鬧的人;
[例句]It looks like an innocent bystander was killed instead of you.
看起來是壹個無辜的旁觀者當了妳的替死鬼。