Explanation:

- The passage discusses communication as a fundamental aspect of daily interactions.

- Blank 5 concerns the idea that speaking a language and effectively communicating in it are not necessarily the same.

1. Devoid: Means completely lacking or free from. It wouldn’t fit grammatically as it would require a preposition.

2. Minus: Means reduced by or lacking. It is more of a mathematical term and doesn’t fit well here.

3. Lacking: This could fit, but grammatically, it would need to follow a structure such as "lacking in."

4. Without: This correctly completes the sentence as it indicates the absence of a requirement.

- The correct answer is "without," which fits the context of conveying a gap between knowing and effectively communicating.