______ left when you get to the end of the street. 
#66195
A
Keep
B
Keeping
C
To keep
D
Kept
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     , and the problem will be worked out.
#66110
A
If you have a bit more effort
B
Having a little effort
C
A bit more effort
D
There being a little effort
____ touch anything unless your teacher tells you to
#65872
A
No     
B
Not       
C
Not to  
D
Don't
__ mix these things together.
#59447
A
Not
B
No
C
Don't
D
You aren't