单项选择题

The Bunsen burner is so named because it is thought ______ by Robert Bunsen, who was German by birth.

A．having been invented
B．to be invented
C．to have been invented
D．being invented
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单项选择题
She is subject to frequent ______ from high spirits to depression.
A．transformation
B．transmission
C．transference
D．transition
单项选择题
______ no further business, the meeting closed at 11:00.
A．There being
B．There is
C．There to be
D．There be
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