甲状腺大部切除术后，呼吸困难和窒息的并发症与下列哪项因素无关

A．气管软化塌陷
B．喉返神经损伤两侧声带麻痹
C．喉头水肿
D．手术创伤的应激诱发危象
E．切口内出血压迫气管

—______ have you been to Thailand since 2004?

—Four times.[ ]

A. How long

B. How many times

C. What time

D. How soon