In the question below, a sentence is given with two

Solution

First blank - we need a plural verb here to agree with the plural subject CELLS. The sentence talks about how the number of connections between the brain cells slowly die during the process of ageing. REDUCE and DECREASE can fit here. Diffuse - spread over a wide area or between a large number of people. Second blank - we need an adverb here to modify the verb WORK. The sentence talks about how some areas of the brain work less successfully. Both EFFICIENTLY and EFFECTIVELY will fit here. RELIABLE is an adjective.