Grammar – Difference Between ‘Have to’ and ‘Should’
grammarverbs
I have a question that what is the difference between following statements.
You have to do this.
You should do this.
I am confused.
Best Answer
This type of wording is often used in requirements manuals, specifications, policies, and procedures. Each such document should clearly define its terms to avoid ambiguity.
If this is from a policy manual that you need to adhere to, you should clarify the exact meanings of these terms.
A somewhat "famous" set of specifications for geeks of the world is the RFC specifications used for the Internet specs and include typical definitions for these types of terms. Here's an excerpt from https://www.ietf.org/rfc/rfc2119.txt, for "MUST" and "SHOULD".
MUST - This word, or the terms "REQUIRED" or "SHALL", mean that the definition is an absolute requirement of the specification. [This is the equivalent of your "have to". - CoolHandLouis]
SHOULD - This word, or the adjective "RECOMMENDED", mean that there
may exist valid reasons in particular circumstances to ignore a
particular item, but the full implications must be understood and
carefully weighed before choosing a different course.
The RFC defines the following words/phrases: "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL".
"he did" is past tense. "should have done." is also past tense, so it agrees and is proper
"should do" is present tense, so in your second sentence there is a tense mismatch between "he did" and "should do". A proper sentence ending in "do" would require you to change the verb tense (and the meaning), for example "He is doing what he should do."
English is a ridiculous language! Maybe Ram should slap whoever created our tense structures!
"What could go wrong?" is more of a hypothetical question about the future.
It can be used rhetorically to support an idea by pointing out that it is low-risk.
It's also sometimes used sarcastically to make fun of an obviously bad idea, e.g. "Closing your eyes while driving - what could go wrong?"
"What can go wrong?" is less hypothetical and more immediate. I don't hear this phrase nearly as often as the other version. However, it might be used for something like troubleshooting some hardware.
In either case, "possibly" is added for emphasis and doesn't change the meaning much.
Best Answer
This type of wording is often used in requirements manuals, specifications, policies, and procedures. Each such document should clearly define its terms to avoid ambiguity.
If this is from a policy manual that you need to adhere to, you should clarify the exact meanings of these terms.
A somewhat "famous" set of specifications for geeks of the world is the RFC specifications used for the Internet specs and include typical definitions for these types of terms. Here's an excerpt from https://www.ietf.org/rfc/rfc2119.txt, for "MUST" and "SHOULD".
MUST - This word, or the terms "REQUIRED" or "SHALL", mean that the definition is an absolute requirement of the specification. [This is the equivalent of your "have to". - CoolHandLouis]
SHOULD - This word, or the adjective "RECOMMENDED", mean that there may exist valid reasons in particular circumstances to ignore a particular item, but the full implications must be understood and carefully weighed before choosing a different course.
The RFC defines the following words/phrases: "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL".