The best time     _      the mall is around six pm. The goods are usually cheap  then.            [ ]

A.  to travel      

B.  to leave          

C.  to go to          

D.  to show up

咬指甲常在（）时出现。

A.情绪紧张

B.情绪放松

C.情绪忧郁

D.情绪高涨