A warning signal suddenly appeared on the screen of my computer, ______ the computer was being attacked by a certain virus.
#90701
A
indicated
B
indicating
C
to indicate
D
having indicated
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Whom do you think Mary will _________ into the matter instead of her?   
#88563
A
have looked
B
have to look
C
have had looking
D
have look
Martin Cooper , a US researcher , was considered _______ the first cell phone .
#96873
A
invented
B
to invent
C
having invented
D
to have invented