1. Yes, there two words ; they have different functions in a sentence.
e.g. Paul`s car is new.
Car - subject
Paul - attribute
2. It`s not necessary to use at the place , because where means in or at the place, part, point, etc., in or at which: The book is where you left it..
I don`t know the exact context, but two steps might mean two marks or impressions made by the foot on the ground; footprints.
As for the word stair, here is the meaning found in the dictionary:
1. stair : one of a flight or series of steps for going from one level to another, as in a building.
2.stairs, such steps collectively, esp. as forming a flight or a series of flights: I was so excited I ran all the way up the stairs.
3. Through means -in this context - while crying / while he was crying
The correct answer is A, meaning from that day on [forward]. The next day means only the following day - tomorrow - it does not imply any more days - just one : the next or the following day.
A. From the day after that = the following days
C. The next day = the following day
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