It is hard to say what kind of person he is．Sometimes he is very friendly; at other times he ___ be very cold．
| A．can | B．must | C．will | D．shall |
---- I’m sorry I stepped outside for a smoke. I was very tired.
---- There is no _____ for this while you are on duty.
| A．reason | B．excuse | C．cause | D．explanation |
No regular advertiser dare produce anything that fails to stick to the ____ of his advertisement.
| A．standard | B．level | C．text | D．promise |
I listened to Dr. Johnson’s lecture about biology, but I failed to get its key ____.
| A．words | B．notes | C．messages | D．points |
It has come to my _____ that some of you have been missing classes.
| A．watch | B．sight | C．view | D．notice |
A month’s _____ is required from whichever party wishes to end the agreement.
| A．message | B．letter | C．sentence | D．notice |