The best way to prevent the air polluting _____ , but the sky is still not clear.
#102116
A
is used
B
are used
C
has been used
D
have been used
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You don't need to describe her, I ___ her serveral times.
#104022
A
had met
B
have met
C
met
D
meet
The pen I _______ I _______is on my desk, right under my nose.
#104524
A
think; lost
B
thought; had lost
C
think; had lost
D
thought; have lost