Everyone should make a contribution         the environment.
#60222
A
to protect
B
to protecting
C
protects
D
protected
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The blue bags ______$8
#59962
A
is on sale
B
are on sale
C
is on sale for
D
are on sale for
How time flies! Three years _________
#52511
A
have passed
B
has passed
C
is passed
D
are past