单项选择题

In ancient times, some catastrophic extinction of species occurred ______.

A．sequentially
B．repeatedly
C．naturally
D．intentionally
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单项选择题
Advanced mammals such as monkeys, apes and humans have brains ______ from ancestors that took to living in the trees.
A．derived
B．progressed
C．terminated
D．advanced
单项选择题
The official was arrested for inability to ______ all his fortune he has enjoyed.
A．clarify
B．intensify
C．verify
D．justify
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