A period
The first word of a new sentence should always be capitalized.
Happy birthday should not always capitalized in a sentence because it is not a proper noun. Example: Marita sent a happy birthday message to her teacher.
If you are referencing yourself, "i" should always, always, always be capitalized. Me = I. When referring to yourself, the "i" should be capitalized even if it is not at the beginning of the sentence. Example: Dave and I went to the store. Remember, just because a word has the letter "i" in it does not mean that the "i" should be capitalized. Example: She used It. (wrong) She used it. (right) The "i" is capitalized only when referring to yourself. In other words, when "I" means "me" or yourself.
A roll model is one who should always strive to set a good example. For example, a role model would not misspell role model.
its a sentence that you present at the begining of your paragraph whilst writing discursive essays. for example: Everything should have a copyright label at the front and back. then you argue for and against that point.
As always you should learn and work very hard at school and improve your walking and writing. For this example only. (ETC).
Yes, it is grammatically correct to end a sentence with "you and I" if it is functioning as the object of the sentence. For example, "This gift is for you and I."
yes, for example 'He may have done it', or 'He should have been writing' which contains four verb forms
When writing out "2-3 millions dollars," the numbers should be spelled out and the dash should be "to. " An example of such a sentence is "The new budget shows that the company will benefit by about two to three million dollars. "
People should not smoke.
Yes, starting a sentence with "then" is grammatically correct, especially when showing a sequence of events or actions. However, it is usually used sparingly to avoid overuse and maintain variety in sentence structure.
Yes. It should be Arctic.