Question

Researchers at the Occidental Research Bureau has struggled for three decades to produce a man-made leaf able to absorb CO₂ from the atmosphere and convert it into chemical energy. Yet now it seems that they have at long last achieved their goal.

Answer 1

Researchers at the Occidental Research Bureau have struggled for three decades to produce an artificial leaf able to absorb CO₂ from the atmosphere and convert it into chemical energy. Yet now it seems that they have at long last achieved their goal.

Step-by-step explanation:

The correct auxiliary in that sentence is have since it is referring to the researchers. In other words, it is a third person in the plural, so the correct auxiliary is have.

The term man-made is not wrong, but it would be better to use the word artificial, which means that nature did not create it.