已知tan θ=3,则sin 2θ+2sin θcos θ-cos2θ=________.
sin 2θ+2sin θcos θ-cos 2θ== ===.
271. Wait for me for a few more minutes. I am _____ to a letter from one of my former classmates at college and will finish writing very soon.
A.replying
B.answering to
C.replying to
D.answering for
食管裂孔疝( )
A.腹部脏器自胸腹裂孔缺损疝入胸腔B.腹部脏器自胸骨旁缺损疝入胸腔C.腹部闭合性损伤,腹腔脏器经膈肌破裂处疝入胸腔D.贲门和胃底经膈食管裂孔疝入纵隔E.膈肌发育薄弱,腹腔脏器向胸腔膨出