单项选择题

A great deal has been done to remedy the situation．（）

A．maintain
B．improve
C．assess
D．protect

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热门试题

单项选择题John is collaborating with Mary in writing an article．（）

A．cooperating
B．competing
C．combining
D．arguing

单项选择题The river widens considerably as it begins to turn west．（）

A．twists
B．stretches
C．broadens
D．bends