In the fragments of the text: “they may lose the desire to master whatever task you are asking them to do” (lines 12-13) and “then you have to do more than just present lessons in the app” (lines 18-19), the verb forms in bold express the ideas, respectively, of 
In the sentence of the text: “However, if you want people to continue using the app, and use it frequently and often, then you have to do more than just present lessons in the app” (lines 17-19), the connector However can be replaced, without any change in meaning, by 
No trecho do terceiro parágrafo – Brazil’s unemployment rate remains at historically low levels despite sluggish economic activity. – a palavra despite equivale, em português a
No trecho do quinto parágrafo – Brazil’s unemployment rate, however, is not fully comparable to jobless rates in developed countries as a large portion of the population is either underemployed or works informally – a palavra as pode ser substituída, sem alteração de sentido, por
No trecho do ultimo parágrafo – In addition, workers not actively seeking a job – a expressão in addition pode ser substituída, sem alteração de sentido, por
Um antônimo para a palavra biggest é
A palavra you que ocorre ao longo do texto refere-se a um leitor ideal, que é um
No trecho do segundo parágrafo do texto – All of these people are likely to get their first impression of the company through their interactions with you. – a palavra likely indica
No terceiro parágrafo, a expressão aside from em – In fact, aside from better public health, one of the major benefits of developing sanitation solutions for the developing world… – equivale a
No segundo parágrafo, o termo while em – GOES satellites are owned and operated by the National Oceanic and Atmospheric Administration (NOAA) while the National Aeronautics and Space Administration (NASA) manages the design, development and launch of the spacecraft. – é corretamente substituído por
