[Grammar] the effects of caffeine wear off after a short time

[kadioguy]

[From a TOEIC test]

This is Jim Johnson with Travel Talk. It's summer and it's vacation time. For some people this means long hours in the car and on the highway. Here are some tips to help you stay safe while on the road. First, the Do's. If you're traveling with more than one driver, try to switch drivers occasionally so that you don’t spend too much time behind the wheel. Remember to stop frequently and take a break. Make sure you know the signs of drowsiness: missing road signs, difficulty focusing, and yawning. Now the Don't's. Don't count on distractions such as the radio or an open window to keep you awake. And even though a cup of coffee might give you a lift, remember that the effects of caffeine wear off after a short time. Finally, don't drive between midnight and morning. Tune in again tomorrow when we'll talk about vacation destinations that both adults and children will enjoy.

[Source]
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How about "... the effects of caffeine will wear off after a short time"?

a. ... the effects of caffeine wear off after a short time.

b. ... the effects of caffeine will wear off after a short time.

I assume:

1. Both work here.

2. Sentence (a) contains more certainty than (b).

3. However, in this context both practically mean the same.

Are these right?

 

[5jj]

Yes, though (a) is more than just certain. The information is presented as a fact.

 

[kadioguy]

[From a TOEIC test]
[...]
Tune in again tomorrow when we'll talk about vacation destinations that both adults and children will enjoy.

c. ... we'll talk about vacation destinations that both adults and children will enjoy.

d. ... we'll talk about vacation destinations that both adults and children enjoy.

I think the same for (c) and (d). However, it seems to me that (c) is more natural (maybe because it is a recommendation).

Is that right?

 

[5jj]

I think the same for (c) and (d).

So do I, but neither is 'more natural' than the other. Neither is, in itself, a recommendation.

 

[kadioguy]

I think the same for (c) and (d).

If you don't mind, could you tell me whether both "for" and "to" work here?

 

[5jj]

Only 'for' works for me.