a) TV - There is an interesting film on TV. The correct answer is 'a TV' because we use the article 'a' before TV because it is a specific television set.
a) a big city - He lives in a big city. The correct answer is 'a big city' because the article 'a' is used before big city as it refers to any large city in general.
a) good knowledge - You need good knowledge of English to get this job. The correct answer is 'good knowledge' because 'knowledge' is an uncountable noun and does not require an article before it.
a) sugar - Do you take sugar in your coffee? The correct answer is 'sugar' because it refers to the substance in general, not a specific quantity or type of sugar.
a) bad luck - We lost the match. We had bad luck. The correct answer is 'bad luck' because 'luck' is an uncountable noun and does not require an article before it.
b) litter - You shouldn’t drop litter in the street. The correct answer is 'litter' because it is used in a general sense to refer to waste or garbage.
b) apples - I eat apples almost every day. The correct answer is 'apples' because it is a countable noun and refers to the fruit in general.
b) work - He is looking for work at the moment. The correct answer is 'work' because it refers to the concept of a job or employment in general.