Dr is the abbreviation of doctor, that is, doctor (highest degree). You must get the title before you can call it. I'm studying for a doctorate. By the way: postdoctoral is not a degree, but a title for a doctor who works in a certain place.

Germans usually don't adDress professors by prof.dr I read a letter to Aachen called dr.Prof It is reported that the reason is that German professors must be doctors, and the habit of addressing professors by dr is more similar to that of Yu Xiansheng.

form

Cardinal words: words representing numbers are called cardinal words. Its form is as follows:

(1) From1—10 One, two, three, four, five, six, seven, eight, nine, ten.

(2) from11-19 eleven, twelve, thirteen, fourteen, five, sixteen, seven, eight, nine.

Except eleven, twelve, thirteen, five and eighteen are special forms, fourteen, sixteen, seventeen and nineteen are all composed of their single-digit forms followed by the suffix -teen.