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.
B. Compition
How to spell it correctly- Competition
The definition of a meter: Distance traversed in vacuum by light in 1/299,792,458 of a second.
According to this light travels 299,792,458 meters in a second. A nanosecond is 1 billionth of a second so light travels 299792458 / 1,000,000,000 meters in a nanosecond or 0.299792458m. (In a vacuum).
I'm pretty sure it's "the baby cried" because an independent clause can stand alone and that can stand alone.