The first law of thermodynamic holds because, so far, there has not been any evidence against it. 

Even though it's only the first lesson, I can tell this is going to be a boring module.

Person A: Namibia has invested a lot of money on its new education system, but the results are still not up to standard. Perhaps we should rethink our approach.

Person B: But, it would be wasteful to abandon the system now, since so much money and time was invested in it. 

In life, you either choose to dedicate yourself to your family or your

Person A: Namibia is facing serious challenges with drought and water scarcity, which affects the agriculture sector.

Person B: But Namibia has one of the most beautiful deserts in the world.

Al + HCl →

Al + O₂ →

при нагріванні Al + HNO_3(конц.) →

MnO₂ + Al →