.________they were singing, the teacher came in. 
#72179
A
Before
B
after
C
As
D
Until
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The expert offered us another piece of advice,_____of great help to our program. 
#73723
A
I think it is
B
I think which is
C
which I think it is
D
which I think is 
____ are you going to be ____ you grow up?
#41314
A
What, while
B
What, when
C
When, how
D
When, what