单项选择题

After they ______ the first super computers in the 1940s, scientists and engineers began to develop ways to create networks.

A．create
B．created
C．have created
D．has created

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The flight scheduled ______ at 9 a. m. was delayed four hours due to the bad weather.

A．to take off
B．take off
C．taking off
D．to be taken off
单项选择题
This website may contain links to other websites ______ privacy practices may be different from ours.

A．that
B．which
C．who
D．whose
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