During the period of recent terrorist activities, people _____ not to touch and unattended bag.
| A．had always been warned | B．were always being warned |
| C．are always warning | D．always warned |
It is worth considering what makes “convenience”foods so popular，and ______ better ones of your own．
| A．introduces | B．to introduce |
| C．introducing | D．introduced |
I feel greatly honored _________ into their society．
| A．to welcome | B．welcoming |
| C．to be welcomed | D．welcomed |
The message is very important，so it is supposed _________ as soon as possible．
| A．to be sent | B．to send |
| C．being sent | D．sending |
You can use that ____ tire and it is ______ .
| A．spare; free | B．spare; spare | C．free; free | D．free; spare |
— Is the man our sales-manager?
— No, it ______ not be him he never plays cards.
| A．must | B．can | C．will | D．may |