Mr. Sanders _______ on a business trip to Tokyo until the end of this week, so he will not be able to complete the sales report as scheduled.
A. would have been
B. will be
C. will have been
D. was being
The answer is B. But I wonder,
- Why is C wrong?
- Why can't until be used with future perfect tense?
- What is the difference between the following:
He will be on a business trip.
and
He will have been on a business trip
Best Answer
I don't think C is strictly "wrong". But first lets explore the differences in the two tenses:
For me, the simple future tense just states an action will occur in the future.
Whereas the future perfect tense states an action will end before some time in the future. This cut-off point happens before some other future action.
Since the above sentence doesn't have another action in the future, it's ungrammatical. The following would be okay
It's important to note that the future perfect tense does not mean the action will occur in the future. It only means it will end before some time in the future. The action could have actually started/ended in the past, present, or future, but the emphasized point is that the action ends before the other future action being compared to.
Anyways, the problem with combining "until" with "will have been", comes down to operator scope, the phrase which is being modified by the construction. For example:
The scope of "until" is "I will be in Tokyo"; until is applied to that whole phrase.
The "will have been" construction works like:
The "until" construction works like:
Here is a sentence that is good English to me, and this is how I would parse it. (...) indicates the scope of "will have been". [...] indicates the scope of "until".
A problem happens when (...) becomes too long. Basically, the "will have been" operator gets weaker and weaker as the sentence goes on. Eventually the scope of "will have been" will end. Look at the following sentence which is awkward English:
Because the clause is so long, in my mind I don't include "until the end of this week" in the scope of "will have been". And the above sentence structure doesn't make much sense in English because "until" always takes an action that has a duration. But the future perfect tense is describing a single point in time.
To summarize: