The basic causes are unknown, although certain conditions that may l-考呗网题库移动版

单选题 The basic causes are unknown, although certain conditions that may lead to cancer have been __________

A．identified
B．guaranteed
C．notified
D．conveyed

参考答案A

解析: A。虽然确定了一些可能导致癌症的条件，但是本质的原因还是不清楚。
考查动词辨析。identify意为“确定，确认”；9Ilamntee意为“确保”；notify意为“通报”；convey意为“传达”，故A符合句意。

单选题 Bill is an example of a severely disabled person who has become __________ at many survival skills．

A．proficient
B．persistent
C．consistent
D．sufficient

单选题 The town planning commission said that their financial outlook for the next year was optimistic．They expect increased tax

A．efficiency
B．revenues
C．privileges
D．validity

单选题 The ties that bind us together in common activity are so __________ that they can disappear at any moment．

A．trivial
B．fatal
C．tentative
D．feeble