Before submitting a document to others, it is important to ensure that it is error-free and well-written. This can be achieved by using various tools and commands in word processing software. Among the given options, the command that should always be used before submitting a document to others is the "Spelling and Grammar" command.

1. Spelling and Grammar check:
- Before submitting a document, it is crucial to check for spelling and grammar errors. Spelling mistakes and grammatical errors can make the document difficult to read and understand, which can negatively impact the overall impression of the document.
- The "Spelling and Grammar" command in word processing software helps to identify and correct errors in spelling, grammar, punctuation, and sentence structure.
- It highlights the errors and provides suggestions for corrections, allowing the writer to make necessary changes and improve the quality of the document.
- By using this command, the writer can ensure that the document is free from common mistakes and is more professional and polished.

2. Importance of using the Spelling and Grammar check:
- Using the "Spelling and Grammar" command is important because it helps to catch errors that might have been overlooked during the writing process.
- It ensures that the document is coherent, clear, and error-free, which enhances its readability and credibility.
- By using this command, the writer can avoid embarrassing mistakes, such as typos, misspellings, and grammatical errors, which can undermine the overall message and impact of the document.
- It also helps to maintain consistent language usage and style throughout the document.
- Additionally, the spelling and grammar check can assist non-native English speakers or those who struggle with language proficiency in identifying and correcting errors.

In summary, the "Spelling and Grammar" command should always be used before submitting a document to others. It helps to identify and correct spelling, grammar, punctuation, and sentence structure errors, ensuring that the document is error-free, coherent, and professional.