After the question mark, you should add a space.
Example.
Wrong - Should I eat a salad?I do not know!
Right - Should I eat a salad? I do not know!
And grammer is spelled "grammar"
Answer:

(ii) TR = MR
Explanation:
TR = MR in perfect competition beacuse the firm was price-taker.
Explanation:
I don't really get the first part but heres 2nd part.
2. nueve IV + V = IX
3. dos VIII - VI = II
4. diez III + VII = X
5. cuatro VI - II = IV
6. ocho IX - I = VIII
7. seis II × III = VI
8. sinco X ÷ II = V
Answer:
D. All of the above are effective critiques.
Example:
You mean,
Which of the following is not an example of an effective critique of Dr. Martin Luther King’s “I Have a Dream” speech?
a. I could tell he was passionate about his topic, but I found Dr. King’s speech to be too long and, at times, rather boring.
b. One can feel Dr. King’s passion for his topic, however the introduction to his talk could have been shortened in order to better keep the audience engaged.
c. Though, at times, wordy, Dr. King’s passion for his topic and the historical and religious imagery he uses evoke strong emotion and keep his audience engaged.
d.All of the above are effective critiques.