■ long distance

可以作为副词短语使用。

• He telephoned her long distance from New York.他从纽约给她打长途电话。

• unaware 与 unawares
• under
• under-
• underestimate
• undersell
• unhuman
• unilateral
• unilateral 与 one-sided
• uninterested
• union
• unite
• united states
• university
• unless
• unlike
• unload
• unsatisfied
• until
• until
• until
• uphill
• up north
• upon
• upper
• up to