Some synonyms for requirement are DEMAND/condition//need and must, something that u MUST do or NEED to do. <span />
Both inventions were done by teenagers at their times.
Both inventions claimed to help the environment: Boyan Slat's machine would clean up trash floating in ocean. Duro-Aina Adebola, Akindele Abiola, Faleke Oluwatoyin, and Bello Eniola proposed power generation from urine that would not create carbon monoxide.
Unfortunately both inventions were also challenged by more established scientists and engineers.
An adjective clause functions as an adjective, that is, it gives some information about a noun in a sentence (or a pronoun) ( information which is not an action).
The noun modified here is "knife" and the information about the knife, that is the complete adjective clause is "<span> that his dad gave him.
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<span> 3(2x - 3) + 4(2 - x) = 0 6x - 9 + 8 - 4x = 0 2x - 1 = 0 2x = 1 x = 1/2. </span>