下列运算中，错误的是[ ]
A．aa2=a3
B．2a+3b=6ab
C．a4÷a2=a2
D．（﹣ab）2=a2b2
答案：B
试述甲亢危象的处理原则。
One of the most popular Korean TV dramas of all time, Dae Jang Geum(《大长今》), _______in Hunan TV Station recently.
A．will release
B．are releasing
C．has been released
D．has released
