from outer space
by the looks
by one's appearance都可以表示根据外表（长相）来…
例1.我们不应该从外表来判断一个陌生人.
We should not judge a stranger by his or her appearance.
例2.告诉他不要从外表判断一个人.
Tell him not to judge people by their looks
In externals从外表看
From the looks of one‘s从某人的外表（长相）看
例3.从外表上看,她们是两个丝毫不引人注目的姑娘.
In externals,they were two unobtrusive girls.
例4.从外表看上来,他就是那种没车、没家、没干净衣服,而且没钱的人.
From the looks of him,he had no car,no home,no clean clothes,and no money.
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