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.

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.

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.

thtahth hg nd d

explanation:

gfdhj rs tyh6r h ts eqagdas   d dy d   w 5js   tydtrs tfs4gtehtyhh

i think the answer is b