________ many times，I still didn't know how to operate the machine.
A．Having taught B．Having been taught C．Being taught D．Teaching
Tony is said ________ to New York, and now he is studying medicine in a famous college in America.
A．have gone B．to have gone C．going D．to go
Today the Red Cross provides a number of services for the public, such as helping people________, teaching first aid and providing blood.
A．in need B．in return C．in preparation D．in anger
Everyone in the class is expected to________in the discussion.
A．participate B．attend C．donate D．declare
Please post this letter in the post office nearby, and ______, I will get two tickets in the train station.
A．in meantime B．on the meanwhile C．in meanwhile D．in the meantime
Many people are not________the danger of their children's bad habits, which lead to failing to make their dreams come true.
A．well aware to B．very aware of C．aware that D．well aware of
