21. --- Has Sarah left her office? She said she would attend my birthday party?
--- She ____, for she is a woman always keeping her word.
A. might have left B. must have left C. should have left D. must leave
22. According to the latest report, human beings are _____ for the abnormal climate around the whole world.
A. to be blamed B. to be blaming C. to blame D. blaming
23. --- Where is Mary? She said she would meet me at 6 o’clock.
--- She seems ____ with Mrs. Smith in the office.
A. to talk B. to be talking C. to have talked D. talking
