比较现在完成时与现在完成进行时的英文

mary is still writing letters. she's been writing letters all day

• 比较:    compare; compare w ...
• 现在:    now; at present; t ...
• 完成:    accomplish; comple ...
• 时:    shí]
• 与:    take part in; part ...
• 进行时:    progressive tense