How can supplies of metals such as copper and aluminum remain healthy even though there is a dwindling amount in the earth's crust?

Imagine ? person stepping on a pin and pulling his or her foot way look at the réfléchir arc of the scenarios below

Which way do the nitrogenous bases in dna pair up? a. a and g; t and c b. a and c; t and g c. a and t; g and c d. a and a; t and t; g and g; c and c

What type of reaction is photosynthesis