It depends on what your book is going to be about! My advice is to stop worrying about some sort of perfect first sentence and just write your book -- then you can go back and figure out a great first sentence based on what you have written.
The grammar depends on the meaning of the sentence. If it is talking about the future, it would be, 'This will be a great adventure'. If it is talking about something that has already happened, it would be, 'This would have been a great adventure.'
If you capitalize the first letter of the sentence and place a period at the end, use an apostrophe for the contraction for 'it's', it is a correct sentence: It's going to be a great night today. Although correct as a sentence, it would make more sense if it said: It's going to be a great night tonight.
My assets are great. It would be an asset to me if you did that.
A great and descriptive sentence containing the common verb accompany would be "My mother accompanied me to the train station on my first day of school".
Chimpanzees are very smart, for example...they can recognize their own reflection in a mirror, while other animals would not be able to.
Nice, pleasant, heart-warming, dreadful, and frightful are words that could replace great in the example sentence provided above.
Answer: No. They would not.
If speaking about a grandmother and great-grandmother, yes, lower case. But when writing to your grandmother, it would be upper case. Also, if either is the first word of a sentence it is first-letter uppercase.
hell no
absolutely not. if it did it would get killed
The complexity of this question is to great for an adequate answer
I would say that this is a great example.