Answer:
First parts only: Not accustomed to unit of math teachings
B: It's more effective to use colored chalk
C: Its difficult to memorize all of these relations
D: It's essential to distinguish the elements of the elements of a set from the "non-elements."
E: It's important to point out that elements of a set need be individual, but may themselves be sets.
F: It's impossible to determine the exact image in that case.
G: It's desirable to have a more simplified system of notation.
H: It's clear to see that the meaning of an expression depends on its context.
I: It's compulsory to give your full name.
J: It's necessary to do the measuring as accurately as possible.
K: Its permissible to cut [=] into 2 or 3 parts.
It's impossible to read your writing.
It's useful to use a heating pad.
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It's silly to get upset over small things.
It's difficult to solve this equation.
It's important for your health to drink lots of liquids.
Its unfair to criticise him.
From my understanding all you are doing is converting liters to grams. It says you have one leader of hydrogen peroxide. 1 liter equals 1000 grams. And if it is asking how many grams are in 1 liter hydrogen peroxide then the answer would be 1000 grams
Answer: The author wants to inform readers about trees.