A man and a woman at an outing talking to each other .
A man and a woman are discussing global warming .
A man and a woman at an outing talking to each other.
A man and a woman are discussing global warming.
The man and woman could be discussing anything, no suggestions as to the nature of the topic being 'global warming'.
The man and woman could be discussing anything , no suggestions as to the nature of the topic being 'global warming ' .