Great as Newton was, many of his ideas _____today and are being modified by the work of scientists of our time.
| A．are to challenge | B．may be challenged | C．have been challenged | D．are challenged |
Having checked the doors were closed, and ___ all the lights were off, the boy opened the door to his bedroom.
| A．why | B．that | C．when | D．ours1 |
It is none of your business __________ other people think about you. Believe yourself.
| A．how | B．what | C．which | D．when |
You can only be sure of __________ you have at present; you cannot be sure of something __________ you might get in the future.
| A．that; what | B．what; / | C．which; that | D．/; that |
A warm thought suddenly came to me __________ I might use the pocket money to buy some flowers for my mother’s birthday.
| A．if | B．when | C．that | D．which |
These shoes look very good. I wonder __________.
| A．how much cost they are | B．how much do theycost | C．how much they cost | D．how much are they cost |