Complete the given stems with the prefix which means the same as the word in brackets. There is an explanation to guide you.

1.	-god (half) = a person who is partially mortal and partially god
2.	-professional (similar) = a trained worker who is not a member of a profession but who assists a professional
3.	-royal = (not real) having the power but not the rank or title of a king
4.	atitis (skin) = a disease in which the skin is red and painful
5.	atologist (skin) = a doctor who studies and treats skin diseases
6.	atology (blood) = the scientific study of blood and the body tissues
7.	bar (equal, identical) = a line drawn on a weather map joining all the places which have the same air pressure
8.	biology (nerve) = the branch of biology that deals with the anatomy of the nervous system
9.	cellular (within) = located or occurring within a cell or cells
10.	charge (over, above) = a charge in addition to the usual amount paid for something
11.	cracy (god) = the belief in government by divine guidance, a country that is ruled by religious leaders
12.	military (similar) = describes a group which is organised like an army but is not official and often not legal
13.	nox (equal) = either of the two occasions in the year when day and night are of equal length and the sun is directly above at the equator
14.	ology (sound) = the study of sounds in a particular language or in languages generally
15.	ophilia (blood) = a rare blood disease in which blood continues to flow after a cut or other injury
16.	plus (over, above) = an amount which is more than is needed
17.	psychiatry (nerve) = the branch of medicine dealing with mental disorders of the nervous system
18.	sex (single) = intended for use by both males and females
19.	spect (backwards) = thinking now about something in the past
20.	tope (equal, identical) = a form of an atom which has a different atomic weight from other forms of the same atom but the same atomic number