关于血清特异性抗体检测的概念，下列哪项是错误的（）

A.IgM型抗体的检出有助于近期感染的诊断

B.IgD型抗体滴度升高提示既往感染

C.疾病早期抗体滴度低，后期滴度显著升高

D.在疾病恢复期比早期抗体滴度升高4倍以上有诊断价值

E.回忆反应是由于既往感染或预防接种者再感染另一病原体时使原有抗体滴度升高所致

A punctual person is in the habit of doing a thing at the proper time and is never late in keeping an appointment.
The unpunctual man, on one hand, never does what he has to do at the proper time. He is always in a hurry and in the end loses both time and his good name. A lost thing may be found again, but lost time can never be regained. Time is more valuable than material things. In fact, time is life itself. The unpunctual man is for ever wasting and mismanaging his most valuable asset as well as other’s. The unpunctual person is always complaining that he finds no time to answer letters, or return calls or keep appointments promptly. But the man who really has a great deal to do is very careful of his time and seldom complains of want of it. He knows that he can not get through his huge amount of work unless he faithfully keeps every piece of work when it has to be attended to.
Failure to be punctual in keeping one’s appointments is the sign of disrespect towards others. If a person is invited to dinner and arrives later than the appointed time, he keeps all the other guests waiting for him. Usually this will be regarded as a great disrespect to the host and all other guests present.
Unpunctuality, moreover, is very harmful when it comes to do one’s duty, whether public or private. Imagine how it would be if those who are put in charge of important tasks failed to be at their proper place at the appointed time. A man who is known to be habitually unpunctual is never trusted by his friends or fellow men.

According to the third paragraph, when you are invited to dinner, you should arrive there ______.

A. after other guests have arrived
B. before all other guests
C. at the appointed time
D. after the host has got things ready