Can a person with o+ and o_ have a a_child?can two people with o _ and o+ make a_

The short answer is ,
no. 

 Human blood types are referred to as being "ABO" -
based upon their containing the "A'" protein (or "antigen"), the "B" protein, both
proteins ("AB") or neither A or B proteins (called"O" ) and the additional "+" or "-"
are describing a second factor called the "Rh" factor. The + means that the Rh factor is
present, while the - means it is absent.

Blood type is
determined by the presence of two alleles, one donated from each parent, which together
form the blood type of the offspring.

Type "AB" blood would
have alleles of one "A" and one "B"

Type "A" blood could be
one "A" allele and another "A" allele or it could be one "A" allele and one "O" (since
"O" is recessive, the "A" would be expressed)

Type "B"
blood, similarly, could be "BB" or could be "BO"

Type "O"
blood could ONLY be two "O" alleles.

Therefore type "O"
parents (both "OO", could only make an "OO" child)

The Rh
factor could occur as in your question, since the negative factor is recessive and a
heterozygous positive (one "+" along with one "-" ) and a recessive (two "-" alleles)
could have a combination in which a "-" from each parent unites to form the ofspring's
Rh factor.

Back to your question. Parents with AO and
OO..........AA and OO...........AO and AO...........AA and AO..........AA and
AA.........AA and AB...........AO and AB.........and ..........AB and AB..........can
ALL have a type "A" offspring...........but no two parents of type "O" can have an "A"
offspring.