Modals: Logical Conclusion/Inference and Negatives

[Erin]

Look at this sentence:

Kathy's office is dark, the coffee on her desk is cold, and her answering machine shows seven unheard messages. Kathy must not have come in to the office yet.

This usage of "must" is what we call "logical inference" or "logical conclusion."

When we draw a conclusion based on information, we can use must.

For example, if Sally has left the house, but the radio is still on, we can say "She must have forgotten."

If we see somebody who has just come back from a long day at work with no break, we can say "You must be tired."

[Vaya]

Kathy must not have come in to the office yet.

I know what 'must' means and it's OK... but I was taught that for negative deduction we use can't and 'must not' means prohibition... Is it true? Or I was taught wrong things?

Thanks, Renata

[Erin]

Are you sure this is the rule you learned?

"could have done it" (possibility)

and

"could NOT have done it" (logical conclusion)

have different meanings,

but must/must not do not. In fact, it's quite common to use negative "must" for conclusions about "negative" things:

Jo hasn't said anything to me yet. She must not know it's my birthday.

That makes sense to you, right?

Erin

[Vaya]

Are you sure this is the rule you learned?

Yes, I am sure. I checked 4 grammar books I have. All of them tell the same: mustn't = prohibition, not allowed, very bad idea.

"could have done it" (possibility)
and
"could NOT have done it" (logical conclusion)

I have never heard about it. I think I am lost. Again. I love English but I also hate it. There are so many variants of it! English English, American English, TOEFL English, Written English, Spoken English, Internet English, (in)formal English, lawyer English, newspaper English, slang English, Bush English, native English, foreign English...

Ah... Renata

[Erin]

Originally posted by Vaya

... Bush English ...

But at least this English makes us laugh!!

[atnoon]

What is "Bush English" mean?
English spoken by Bush (the US president)?

[Erin]

Yeah, I think that's what Renata meant.

[emil_diankov]

Dear friends,

Could you tell me plese why in the sentence:
[While their] name [implies] [that] are whales, pilot whales [are] actually dolphins.
the right answer is B?
name - 3th singular?
emil_diankov@yahoo.com
Thank you in advance

[Vaya]

Could you tell me plese why in the sentence:
[While their] name [implies] [that] are whales, pilot whales [are] actually dolphins.
the right answer is B?

This post should be in toefl grammar section. Next time be sure to post your posts in the wright forum.

I believe that the answer isn't B, the answer is C.
That -> that they. We miss a subject in the that-clause, don't we?

Renata

[FrutZle]

Originally posted by emil_diankov

[While their] name [implies] [that] they are whales, pilot whales [are] actually dolphins.

They is missing
name is singluar because you're talking about a group, not the individuals as in "their names are Tom, John and Annie"
Because you're talking about whales (more than one) you say their and are