sentence 1: How do I know if I'm good?
 sentence 2: How do I know what I'm good at? sentence 1: Should I buy an iPhone?
 sentence 2: Should I buy an iPhone 6? sentence 1: Does 'empty' space have mass which is displaced by matter?
 sentence 2: Does 'empty' space consist of 'stuff' which is displaced by matter? sentence 1: What's the difference between anthropology, ethnography and sociology?
 sentence 2: How do Sociology and Demography differ?
not same meaning
not same meaning
same meaning
not same meaning