How the fire in the dancing hall started _________ a mystery.
#100979
A
to remain
B
remains
C
is remaining
D
is remained
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After living there for one year, they have ____ there. 
#102985
A
accustomed to working
B
accustomed to work
C
been accustomed to work
D
been accustomed to working
----Have you got your test result?    ----Not yet. The papers _____.
#100928
A
are still being corrected  
B
are not correcting
C
have already been corrected  
D
have not corrected