David _____ a customer when the fire started．
| A．served | B．was serving | C．had served | D．would serve |
He is the only one of the students who _________ a winner of scholarship for 3 years.
| A．is | B．are | C．have been | D．has been |
Parents ____ bring up their children under 16 and educate them properly.
| A．could | B．may | C．might | D．ought to |
All of us found _____ necessary to learn a foreign language.
| A．this | B．that | C．it | D．what |
I used to _____ bed at nine. Now I am used to ____ bed at ten.
| A．go, going | B．go to, going to | C．go to, go to | D．going to, going to |
The life of Milu ____ at present.
| A．is been studied | B．is being studied | C．was being studied | D．have been studied |