单项选择题

Most environmental problems exist because adequate measures for preventing them （）taken in the past

A．was not
B．were not
C．were not being
D．had not been

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Supposing this ship（）do you think there would be enough life jackets for ail the passengers

A．was sinking
B．has sunk
C．were to sink
D．sunk
单项选择题
I know nothing about his journey（）he was likely to be away for three weeks

A．if
B．unless
C．until
D．except that
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