E-readers are often more ... than printed books because an e-reader allows us to store thousands of books while it is only as heavy as a single book.

A. expensive          B. inexpensive          C. convenient          D. inconvenient

You should ... the batteries fully before using the smartphones.

A. apply          B. display          C. store          D. charge

An e-book reader is convenient, it is used ... eletronic books, newspapers or magazines.

A. read          B. to read          C. reading          D. to reading

'...' means 'made by humans'.

A. valuable          B. useful          C. artificial          D. helpful

Mark the letter A, B, C, D to indicate the word whose underlined part differs from the other three in pronunciation in each of the following questions.

A. graduate          B. communicate          C. laptop          D. valuable