--The prison was ___________ fire last night.
--Someone must have set fire___________ it.
| A．on ; with | B．on ; to | C．over; with | D．should |
So far nobody has provided ______ hard evidence to support their claim that they have seen _______ UFO.
| A．an; a | B．the; the | C．不填；a | D．不填；an |
—sss，you haven't been acting like yourself．Everything is OK?
—.
| A．Sure, it is | B．I'm fine，thanks | C．That's good | D．It's a pleasure |
I am _____ about what I say because careless remarks are likely to hurt others' feelings．
| A．enthusiastic | B．concerned | C．doubtful | D．cautious |
Apple's iphone4S disappointed its fans，its later success was beyond what people could expect．
| A．When | B．As | C．Unless | D．While |
With the nuclear crisis worsening in Iran, the world's attention is fixed again onis called the Middle East．
| A．which | B．that | C．what | D．it |