Marie witnessed everything but it is amazing that she______ have said nothing about the murder.
| A．should | B．may | C．must | D．can |
One of the most important questions they had to consider was _____ of public health. 
| A．what | B．this |
C．that | D．which |
Encourage your children to try new things, but try not to ___ them too hard.
| A．draw | B．strike | C．rush | D．push |
The computer was used in teaching. As a result, not only, but students became more interested in the lessons.
| A． | saved was teachers' energy | B． | was teachers' energy saved  |
C． | teachers' energy was saved | D． | was saved teachers' energy |
The children all turned ____ the famous actress as she entered the classroom. 
| A．looked at | B．to look at |
C．to looking at | D．look at |
Edward, you play so well. But I ______ you played the piano. 
| A．didn’t know | B．hadn’t known |
C．don’t know | D．haven’t known |