Oxygen levels on Earth skyrocketed 2.4 billion years ago, when cyanobacteria evolved photosynthesis:[…]. The evolutionary precursor of photosynthesis is still under debate, and a new study sheds light. The critical component of the photosynthetic system is the “water-oxidizing complex”, made up of manganese atoms and a calcium atom.

Young boys and girls Are level now with men.

This is essential in plural, heteroglot communities, if the school is to be inclusive, and is essential in those school subjects which are contentious and contended.

an ill-begotten scheme