根据拼音填写出相应的汉字。
险zǔ____ 景zhì____ 雄jiàn____ 回huán____
You should return the book____the library on time.
①(2x+3y)(2x﹣3y)
②(﹣x﹣2y)(x﹣2y)
③(x2﹣ 12 )(x2+ 12 )
④(2a+3)2
⑤(a+2b﹣c)(a﹣2b﹣c)
⑥(a2+2b﹣c)2.
They had some ____ yesterday.