Present continuous vs will + infinitive
The body of this question is divided into four sections: Exercise, Theoretical context, Answer and Questions. I believe this is the right site to ask given that this is a question about "word choice and usage" (from the help center).
Exercise
In this textbook I'm working on, I encountered an exercise in which I must choose one of the following sentences:
a) I will do my packing this afternoon, if I can find my suitcase.
b) I am doing my packing this afternoon, if I can find my suitcase.
There is no more context surrounding this sentence, it's a multiple choice question.
Theoretical context
In the relevant grammar section is says the following about the two tenses.
Will + infinitive
to predict what is going to happen based on past experience or opinion
You must go to India - you'll enjoy it.
in more formal contexts for arrangements which have been made in some detail
The tour will begin at 9. 30 and all visitors to the site will need to wear good walking shoes.
for decisions which are made on the spur of the moment
I think I'll go to Paris next weekend.
Present continuous
- to talk about activities or events which have already been arranged or are definite. The future continuous can also be used in this context. It is a little more formal.
I'm travelling on the Orient Express to Venice. I'll be travelling on the Orient Express to Venice.
- to avoid going to + go we can use the present continuous form of go instead
He's going climbing in the Alps next summer.
- for surprising or unexpected events
Paula is taking her mother on her honeymoon!
Answer
Given that it's not a prediction, not a formal a context, nor does it seem to be a decision made on the spur of the moment, I lean towards the use of the present continuous.
Investigating the present continuous gives me even greater confidence that this is the right choice, since we're talking "about activities or events which have already been arranged".
However, the solution given in the book is a), "will do".
Questions
- Isn't the book contradicting itself by choosing a)?
- What is the correct answer?
- What did I miss?
Welcome to the site. Your post is a model of how to ask good questions!
As to the answer: The book is correct in that holidays generally need to be arranged, but packing typically does not - unless, for example, you decide on a time with your spouse or a friend to do so.
Arranged in the context of future events generally includes: a meeting time has been set, flight or accommodation has been booked, etc. In other words, arrangements involve contact with other people (or online resources), whereas packing does not.
Nevertheless, there are contexts in which the continuous form is possible or more likely, even for non-arranged events such as packing. For example, in reply to a friends invitation to play tennis this afternoon:
- Sorry, I am doing my packing this afternoon - if I can find my suitcase.
The problem with many multiple-choice grammar exercises is that no context is given and more than one answer is grammatical - as in the present case. The learner has to decide on the most likely context and choose the answer accordingly.