Hair loss is one of those things we still do not understand. Science has， of course， shown that men are more likely than women to suffer major hair loss. Some kinds of hair loss are temporary （暂时的）， an effect of illness. In those cases we can expect the hair to grow back.
It all depends on whether the hair root is alive. If it is not， hair loss is permanent and nothing will help.
Some daily loss of hair is a normal， healthy sign. Most people lose between 40 to 50 scalp hairs each day.
Each of these scalp hairs grows for from two to six years and then rests. About three months later it is pushed out by a new hair growing from the same root.
This is not something that should cause great concern.
Something else we know is that normal hair loss is seasonal， with the most hair loss occurring in the fall. Everyone experiences a normal cycle of loss and growth.
The problem of hair loss results when loss is greater than growth.
The main cause of hair loss in men seems to be accumulation （ 积累） of a hormone（ 荷尔蒙） in the body. When that hormone reaches a certain level， the hair growing period is shortened and hair loss is the result. This is no cure for most cases of hair loss. This， however， is not the end of the world.
According to science，__________. 查看材料
A.hair loss is a normal， healthy sign
B.man should pay special attention to hair loss
C.it"s likely that men have more problems of hair loss
Anyone who has ever attended a university knows that the quality of lecturers varies greatly. A few are very effective communicators， conveying the substance of their lectures clearly and interestingly and inspiring students to want to know more about the
It could， of course， be argued that students are not competent to evaluate the academic quality of lectures. If anyone should evaluate lecturers， it should be their colleagues. However， I am not arguing that students should be asked to comment on the acad
I suspect that many of the objections to student evaluation stem from the fear some lecturers have of being subject to criticism by their students. However， lecturers should see such evaluation as an opportunity to become aware of defects in their lecturi
According to the author， all the students know that__________. 查看材料
A.it is too dull to attend lectures
B.quite a lot of teachers can produce the results students desire
C.they must be inspired to learn
D.there are great differences among the lecturers as to their quality of teaching
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