I have two grammars, ______are of great use. 
#73806
A
all of which
B
either of which
C
both of that
D
both of which
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At the party, John made up a joke,        people burst out laughing.
#69282
A
on which
B
by which
C
at which
D
from which
 Copy the expression___, please, without any change.
#66602
A
as it is
B
such as it is
C
what it is
D
so it is
 He disappeared last month, _______ we have heard nothing of him.
#69495
A
when
B
after which
C
from which
D
since when