Up to Tuesday's attack, the worst school shooting in the U. S. was in March 1998 in Jonesboro,______two boys, aged 11 and 13, shot and killed a teacher and four girls.
| A．while | B．where | C．when | D．then |
No one but the experts in this field can _____ the difference between them.
| A．recognize | B．speak | C．spot | D．predict |
—Who______ it be that is knocking at the door?
—It ______ be Father, but I’m not sure.
| A．can; must | B．can; may | C．must; can | D．may; must |
The meeting we had ________ to _______ us finally.
| A．looked forward; disappointing | B．been looked forward; disappointed |
| C．looked forward; disappointed | D．been looked forward; disappointing |
The great _____ of this computer is that it’s so cheap compared to the others.
| A．power | B．strength | C．energy | D．force |
The difficulty we now meet with is ___________ we can persuade him to tell the truth.
| A．whether | B．that | C．what | D．why |