Testing is a matter of concern to all teachers – whether we are in the classroom or engaged in syllabus/ materials, administration or research. We know quite well that good tests can improve our teaching and stimulate students’ learning. Although we may not want to become a measurement expert we may have to periodically evaluate students’ performances and prepare reports on students’ progress. That is why J. B. Heaton (1988) said “Both testing and teaching are so closely interrelated that it is virtually impossible to work in either field without being constantly concerned with the other.” (p.5) Till now, no one is doubtful about the role and importance of tests in the teaching process. Tests are of various types serving different purposes of the teaching and learning process. However, it cannot be sure that all tests employed are to help teachers and students evaluate and better their teaching as well as learning. Therefore, the question of how to conduct a good test is at all time concerned by teachers as the test is used as a mirror reflecting the real ability and acquisition of their students, and as “a good test can be used as a valuable teaching device” (J. B. Heaton, 1988, p.7) And we, teachers of Vietnam University of Commerce, are not of the exception. We have tried our best to make better and better achievement tests by changing and improving our tests every school year but it seems that the tests have hardly been satisfactory and that we have not met the core issue of this problem. From the author’s point of view, there are three reasons for this.