What must you do when you reach a steady yellow traffic light?
a. slow down by slamming on the brakes.
b. stop before you enter if you can do so safely.
c. yield to cross traffic if you can yield safely.
d. look left, then right, then left again.
when turning left or right, remember to
a. drive no less than 10 mph below the speed limit
b. activate your turn signal 200 ft in advance
c. yield to vehicles and pedestrians in your path
d. take the widest turn possible
you turn right on a red light if you are in the right-most lane, you're turning into the left-most lane on the cross road, and no nearby sign prohibits the turn.
a. may
b. may not
c. must
d. should
at a red traffic light, you must stop
a. unless you're in a hurry
b. by braking rapidly and swiftly
c. before the vehicle next to you stops
d. behind the stop line if there is one
you turn left on a red light if you are in the left-most lane of a one-way street, you're turning into the left-most lane of a one-way street, and no nearby sign prohibits the turn.
a. may
b. may not
c. must
d. must not

As our current atmosphere formed, the concentrations of various atmospheric gases fluctuated. match each gas with the explanation that best describes how its proportion changed during the evolution of the atmosphere.

“dear sir: it is with great reluctance, i trouble you on a subject, which does not fall within your province; but it is a subject that occasions me more distress, than i have felt, since the commencement of the war; and which loudly demands the most zealous exertions of every person of weight and authority, who is interested in the success of our affairs. i mean the present dreadful situation of the army for want of provisions, and the miserable prospects before us, with respect to futurity. it is more alarming than you will probably conceive, for, to form a just idea, it were necessary to be on the spot. for some days past, there has been little less, than a famine in camp. a part of the army has been a week, without any kind of flesh, and the rest for three or four days. naked and starving as they are, we cannot enough admire the incomparable patience and fidelity of the soldiery, that they have not been ere this excited by their sufferings, to a general mutiny or dispersion. strong symptoms, however, discontent have appeared in particular instances; and nothing but the most acitive efforts every where can long avert so shocking a catastrophe.” what’s the central idea?

1u.s. history question! question: how did world war ii change the united states' position in world affairs? i need good explanation to support the answer otherwise i get docked points. real answers only ! you! : )