--- Do you know the reason _________ pilots turn off the plane’s lights before taking off?
---The practice is for the passengers to adjust to the dark _________ an emergency.
| A．why; for fear that | B．for which; in case of |
| C．how; for fear of | D．that; in case |
---Tell us, Mark, what is the cause of the American Civil War?
---Well, is it _______the black slaves wanted freedom?
| A．how | B．why |
| C．because | D．when |
--- I can’t carry the luggage．It’s so heavy.
--- Why not have someone strong enough_______ you a hand then?
| A．give | B．to give |
| C．giving | D．to have given |
Although she brushed the old pot_______, she could not make it completely clean, which made her very upset.
| A．roughly | B．thoroughly |
| C．instantly | D．occasionally |
Mr．Smith is always on time for everything．How ____ it be that he was late for the important meeting?
| A．should | B．can | C．may | D．must |
---Your grandfather still seems very energetic, although he is already in his seventies now.
---Yes, he _______in the army for three years when he was young.
| A．would serve | B．served |
| C．had served | D．has served |