1. There's no main verb: "...the following sentences are also correct."
2. When "too" means "also", it has to follow the thing it qualifies (usually separated by commas) or go at the end of the sentence:
- I, too, can perceive an error in the sentence.
- If it is correct, the following sentences, too, are correct.
- If it is correct, the following sentences are correct too.
When you place "too" just before an adjective, like this, it conveys the meaning of "in excess":
- You're too late. (= You've missed it.)
as opposed to:
- You, too, are late. (= You also are not on time.)
- You're late too. (= You also are not on time.)