Answer:
Well, it is a matter of opinion.
I personally think singles should be able to adopt. Taking into consideration that there are plenty of children out there who deserve a happy life, i can garantee that not every orphanage is supportive enough. Furthermore, we have plenty of single parents, doing a fantastic job is looking after their loved ones. Of course they will need to be at a healthy state to do so.
Im not so sure about gays though. This may not be so positive for the child's psychological health. Children tend to see their firends and the people around them with two opposite genders. You must also think about school life, ususally students first sex ed lesson is in year four, the child may be in a confused state, and bullying may occur.
No wrong ideas, i do support gays. They should have equal rights like everyone else. However, for them to be able to adopt it hink the child must be at a age, where they know what they are facing, as many children do not know what 'gay' is.
Overall, i think singles should be allowed. One day, gays may be too.
Im happy, if i could answer your question. Like i said, its also a matter of opinion.