Well as it apperas from teh title I'm in of some help regarding my english. I am supposed to find and correct any grammatical mistakes visible in these sentences. The hard part is, that i have to explain my corrections
1. The dog wagged it's tail. (i think it's "its")
2. The wolfes were hungry. ("wolves" perhaps?)
3. The police is overworked. ("are" instead of "is"?)
4. She is unhappy to be without a work. (no ideas)
5. He is the only I would ask to help me. ("one" instead of "I"?)
6. The food tastes really well. ("good" instead og "well"?)
7. He said he wanted to go and lie down. Because he felt sick with worry. "lay and not "lie"? and no full stop, perhams a comma?))
8. That ain't no way to talk to a stranger. ("is" instead og "ain't"?)
You are doing well with your homework.

Here are my suggestions though:
1. Remember, when combining words they use an apostrophe to connect them. Such as are not would be "aren't", can not would be "can't", and so on. This can get confusing though since you use an apostrophe to show possession such as if you wanted to say "That is Bree's pikachu", you would add an apostrophe and then put an "s" after it to show that that the pikachu is Bree's possession. "It" is the only one that does not follow this rule. If you say "it's" it means "it is". To show possession of an object that you refer to as an "it", it will have no apostrophe with the "s". So you were right with the sentence.
2. I would explain deeply into number 2, but I'm not doing too well today. The fact of the matter is that you got that sentence right as well. Remember, if you are showing the subject as a group instead of a single subject, you sometimes have to change the lettering especially in the case of words like "calf" you would spell it as "calves" to refer them as a group. "Calfes" is not proper. Good job on this one.
3. Once again, you're correct. "Is" is a word you use when the subject is single. Since you use police as a single word but can also be used as a group word, you should automatically assume in this case that "police" is being used as a group word, hence why you would use "are" in the sentence instead of "is". Another example would be if you were talking about deer. You would not say "is" to connect the deer in a sentence unless you knew for sure that the deer was a single subject instead of a group subject. Example:
"The deer is eating the grass."
Since you used "the" you are saying that the subject "deer" is a single subject, hence why you would use the word "is". Usually in these homework cases, you should be able to pick up if the subject of the sentence will be a singular subject or a plural subject. So don't worry too much about it.

Sorry if I'm being confusing.
4. Take out the word/letter "a" so that the sentence is "She is unhappy to be without work." Another possibility you could do is add "any" so that the sentence would be "She is unhappy to be without any work.
5. I would add the word "one" but not take out the word/letter "I" so the sentence would be "He is the only one I would ask to help me."
6. This has two possibilities as well. You could take out the word "well" and replace the word "good" with it so it would be "The food tastes really good." Or you could take out the word "really" so the sentence would be "The food tastes well."
7. You're correct. Use the word "lay". Do not add a comma. If you wanted, you could even take out the word "and".
8. Replace the word "ain't" (remember ain't ain't a word

lol ) with the word "is". "Ain't" is not proper English. Another example of a word that should not be used in proper English is "ya'll".
For the most part, you understand your homework well. I hope my suggestions help out with your homework. I'm an English geek. I'm majoring in an English degree at my university so when I say that I am a big English geek, you better believe it.

Feel free to PM me if you would like to ask any questions or if you would like me to clear anything up for you.