The threat of any kind of power failure usually puts fear into the hearts of many people.
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The tape recorder can be a very effective aid to teaching if it is used appropriately.
为了能轻松地解决那问题，我们采取了一些明智的措施。
What"s the meaning of the word "defection" (Last Line, Para. 6)（）
A. Customers" betrayal.
B. Service defects.
Customers" protection.
D. Service advertising.
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