— It's said a pianist will perform at Poly Theater on Friday evening. Is it Lang Lang?

— Yes, it _______ him. He _______ for a week.

A．must be; has arrived here

B．maybe; has been here

C．must be; has been here

D．maybe; has arrived here

魏孝文帝亲政后，面对着阶级、民族矛盾日益激化的政治形势，不得不______，推行一些改革措施，如______俸禄制、均田制等。
依次填入划横线部分最恰当的一项是：（）

A．洗心革面 实行

B．改弦更张 颁行

C．痛改前非 施行

D．改弦易辙 履行