Helpful Video Explaining How A Fitting Test Ensures A Perfect Seal

An AE answer: Helpful to a person; helpful for (or helpful in) + a gerund ...the brochure was helpful to you It was helpful to me, but it was even more helpful to my brother. I found the brochure helpful in understanding why the... The brochure was helpful in explaining.... You'll find the brochure helpful for getting from A to B. Is the following a valid sentence? I think it helpful to mention the caveats in the document. If so, how is the meaning different from this: I think it's helpful to mention the caveats in the do... I don't think "double-edged sword" is appropriate in this context because that idiom implies the object is simultaneously helpful and harmful. I'm instead, searching for a word or phrase to describe something that is either helpful or harmful depending on how it is used. Thanks, lingobingo. It was really helpful of him to take the cat to the animal centre on a rainy night. I wonder if this sentence just shows that 'he' provided help in taking the cat to the animal centre, for example, he drove the car and another person held the cat, and it doesn't necessarily show that 'he' took the cat to the animal centre alone.