There are three ways to end a complete sentence:

A period which ends a statement sentence. (.)

An exclamation point which ends a sentence that shows excitement. (!)

A question mark which ends a sentence that asks a question. (?)

This sentence ends with an explanation point. 

We can use context clues in the sentence to help us learn the meaning of "duck". 

"My dad is so tall, he has to duck when he walks through the door so he doesn't hit his head."

If you were really tall, what would you do so that you didn't hit your head on the top of a door when you walk through it? You would probably lower your head. 

The correct answer is "To lower the head". 

We can use context clues in the sentence to help us learn the meaning of "rat". "My brother was doing something wrong, so I had to rat him out to my mom." If your brother had done something wrong, what would you need to do with your mom? You would probably need to tell on him.

We can use context clues in the sentence to help us learn the meaning of "ruler". "I had to measure something.  I got out my ruler to do so." If you are measuring something, what would you need to do that? You would probably need a rectangular device that tells you how long something is.

We can use context clues in the sentence to help us learn the meaning of "log". "My dad cut a tree into pieces and then picked up a log." If your dad cut down a tree and then picks up a piece of it, what would he have picked up? It would probably have been a smaller piece of the tree.

We can use context clues in the sentence to help us learn the meaning of "mug". "My mom made me a glass of hot chocolate in a mug." If your mom made you a glass of hot chocolate in something, what would it have been? It would probably have been a glass to drink out of.

We can use context clues in the sentence to help us learn the meaning of "blue". "My pet fish just died, so I am feeling a little blue." If your pet fish died, how would you be feeling? It would probably be a little sad.

We can use context clues in the sentence to help us learn the meaning of "cake". "I thought the math problem was not very hard.  I told my dad it was a piece of cake." If the math problem was not very hard, what would it have been? It would probably be an easy problem to complete.

We can use context clues in the sentence to help us learn the meaning of "bat". "I was playing in a baseball game.  My coach told me I was next up to bat." If you’re playing baseball and you are next up to bat, what would you be about to do? It would probably be to take your turn hitting.

We can use context clues in the sentence to help us learn the meaning of "ring". "My cousin asked his girlfriend to marry him.  He gave her a ring." If your cousin asks his girlfriend to marry him and gives her something, what would he likely give her? It would probably be a piece of jewelry to wear on her finger.