MISSING MONDAY: NOUN COLLOCATION

Hello readers! Hopefully you had a great weekend. Welcome back for our first Daily Vitamin of the week!

For today's Missing Monday, we are looking for a noun that works in this sentence. Do you know the correct word? 

Sentence 1: She has an excellent __________ of the English language. 

There might be more than one answer; remember that this is a noun, and it must reflect the idea that the person is a master of something (in this case, speaking English). 

Give us your best guess on our Facebook page.

https://www.facebook.com/ZigguratEscuelaCorporativadeIdiomas

Good luck, and thanks for participating!