Why is this and others in this exercise hoti hai but others just hai? Doesn't that just mean "is is"? Can anyone explain please?
'होती है' is used when you're making a generalisation.
'चीनी मीठी है' is saying that some particular sugar is sweet. By including होती however, you are saying that sugar, in general, is sweet.
Actually "chini mithi hai" is correct in casual hindi but when we use proper hindi I mean in grammatical sense then it is "hoti hai" HOPE YOU ARE NOW SATISFIED!!