当x＞1时，不等式x+ $\frac{1}{x-1}$ ≥a恒成立，则实数a的取值范围是（   ）

关于文学常识的表述，错误的一项是（   ）

据《元史·宰相年表》记载，中书省右丞张启元曾“行中书省于平阳、太原等路”，中书省左丞相耶律铸曾“行省于山东”……他们“事毕还朝，其中书省宰执职务依然如故”。这反映出元代（    ）

阅读下列短文，从每小题的三个选项中选出最佳选项。C
    Fire can bum down a lot of trees. It can hurt people too. We must be careful with fire. There are some fire safety rules. To stop fires:

♦We mustn't smoke in the forest.
♦We mustn't play near fires at home.
♦We mustn't play with matches at home.
♦We mustn't play with burning candles at home.
♦We mustn't put clothes on lamps or heaters.
♦We mustn't cook when no adults are at home.

科学发展观是我们进行中国特色社会主义建设必须长期坚持的指导思想，这是因为：