How would you use verse 10 to show that we can trust Jehovah’s promises?

We could ask him, have we ever doubted that the sun rises or sets so that there is no day and night, if we do not question the physical laws, we must doubt that the creator of such laws can fulfill what he promises, let the person meditate on those questions.

In verse 10 a detailed description of the water cycle is made and it is highlighted that the water that falls from the rain does not return to the sky, it does not evaporate until it has nourished the earth and already gave a fruit, we can emphasize to the person after read these texts to him that in the same way any promise or word that Jehovah has made will not come back to him without giving an obvious result. 

If the person has a few more minutes, what publication in the Teaching Box could they use to start a Bible course?

Perhaps we could use the Enjoy Life Forever booklet and use section 2 in part 4 and discuss some of the promises that Jehovah has for us using the images as well.

Also chapter 3 of the book teaches the purpose of God for humanity in paragraph 2 quotes from Isaiah 55:11 also from paragraph 15 onwards it talks about Jehovah’s promises for the future so we could analyze any of them.

We can also use the Listen to God and Live Forever booklet in part 10 where the question is asked how God will bless those who hear him.

Yes also the brochure Good News from God in question 4 we find some of the things that Jehovah will do to end suffering.