An idiom is an accepted phrase or expression that does not mean

literally what it says.
She "threw cold water on" the project.
"Throw cold water on" is an idiom meaning "discourage" or "kill
enthusiasm for." Type the letter of the idiom that is built on the
word "throw" that best fits the following meaning:

a. throw a monkey wrench into
b. throw oneself into
c. throw oneself upon
d. throw open
e. throw over
f. throw together
g. throw back
h. throw in
i. throw away

1. engage in with vigor (A)throw a monkey wrench into

2. give up; abandon; jilt (C)throw oneself upon

3. fail to make use of (B) throw oneself into

4. add free of charge (D) throw open

6. rely on for support (H) throw in

7. revert to ancestral type (G) throw back

8. obstruct by interference (E)throw over

At least some of your answers are wrong. Check them out with Google.

https://idioms.thefreedictionary.com/throw+a+monkey+wrench+into

Thank you, can you let me know which ones I missed?

To answer this question, you need to understand the meanings of the idioms that are built on the word "throw." Here are the meanings of each idiom:

a. throw a monkey wrench into - to obstruct or interfere with something
b. throw oneself into - to engage in something with vigor or enthusiasm
c. throw oneself upon - to rely on for support or assistance
d. throw open - to make something accessible or available to everyone
e. throw over - to give up or abandon someone or something
f. throw together - to hastily assemble or create something
g. throw back - to revert to an ancestral type or characteristic
h. throw in - to add or contribute something as part of a deal or offer
i. throw away - to fail to make use of or discard something

Now, let's match the idioms to their meanings:

1. engage in with vigor - The correct idiom is b. throw oneself into
2. give up; abandon; jilt - The correct idiom is e. throw over
3. fail to make use of - The correct idiom is i. throw away
4. add free of charge - The correct idiom is d. throw open
6. rely on for support - The correct idiom is c. throw oneself upon
7. revert to ancestral type - The correct idiom is g. throw back
8. obstruct by interference - The correct idiom is a. throw a monkey wrench into

So, the correct answers are:
1. a. throw oneself into
2. e. throw over
3. i. throw away
4. d. throw open
6. c. throw oneself upon
7. g. throw back
8. a. throw a monkey wrench into