如图，在△ABC中，∠ABC和∠ACB的平分线相交于点O，过点O作EF∥BC交AB于E，交AC于F，过点O作OD⊥AC于D．下列四个结论：
①∠BOC＝90º＋$\frac{1}{2}$∠A； ②以E为圆心、BE为半径的圆与以F为圆心、CF为半径的圆外切；③设OD＝m，AE＋AF＝n，则S_△AEF＝mn； ④EF是△ABC的中位线．其中正确的结论是____．

新电灯泡的玻璃上常有一点暗红物质以除去灯泡内残留的氧，该物质是（　　）

单词拼写。

Why doesn't the woman choose the black dress?

根据句意，用括号内所给单词的适当形式填空
(1)— Would you like to play computer games with us?
— Yes, with____ (please).
(2)— Could you ____ (fetch) me some hot water, dear?
— Sure, Mom.
(3)Let's raise money to help the____ (disable).
(4)There are many helpful social (社会的)____ (organize) in the world.
(5) She is blind. That is to say, she is ____ (able) to see.