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 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
In the excerpt of the fourth paragraph – Paramagnetic properties are due to the presence of some unpaired electrons – the expression due to can be replaced, without changing its meaning, for
In the text, the word “current” (l.1) means
The word “actual” (l.24) is synonymous with
In the text,
