[译] 飞机很快就飞得看不见了。
[误] The plane was soon out of the sight.

[正] The plane was soon out of sight.
[注] 表示“在视野之外，看不见”，应该说 out of sight, 其中在 sight 前没有定冠词。类似的还有 in sight（被见到），know sb. by sight（跟某人面熟）等。