— Is Jack on duty today?
— It ________ be him. It's his turn tomorrow.
| A．mustn't | B．won't | C．can't | D．needn't |
In summer, food will go bad if_________in room temperature.
| A．leaving | B．left | C．being left | D．having left |
．QQ, _________you can chat with your friends, makes communication easy.
| A．why | B．which | C．that | D．where |
_________fit, we ought to learn more about our body and be careful with what we eat.
| A．Keeping | B．To keep | C．Having kept. | D．To have kept |
Of all the girls, Jane spent_________time and made_________mistakes.
| A．less; fewer | B．much; many | C．the least; the fewest | D．more; most |
How_________I help them to understand when they won’t listen to me?
| A．can | B．would | C．may | D．must |