There are doubts about the usefulness of these tests.这些试验是否有用，人们有所保留。I was persuaded of the usefulness of his new device.我相信了他的新装置的实用性.The index adds appreciably to the usefulness of the book.索引明显地增加了这本书的实用价值....

usefulness的音标：usefulness的英式发音音标为：['ju:sfəlnəs]usefulness的美式发音音标为：['jusfəlnɪs]...

n.有用，有益，有效，效能...

Usefulness includes the fact the negatives have been calibrated.所谓有用,是指在底片上要有标度.The theory is of limited usefulness.这个理论用途有限。The report is of potential usefulness to the government.这个报告可能对政府有用。There are doubts about the ...