The textbook is very costly; I cannot … it to my students.

Analyze the question: We need the word that best completes: "The textbook is very costly; I cannot _ it to my students."

Explain the concept: This tests word choice and collocation (which verb naturally pairs with "it to my students"). The structure is verb + object + to + person.

Check each option:

• A. commit: You can "commit something to someone" (entrust), but it doesn't fit the idea of suggesting a book to students. Unnatural here.
• B. afford: This looks tempting because the book is costly. But "afford" does not take the structure "afford it to my students." You would say "I cannot afford it" (without "to my students"). So it doesn't fit grammatically.
• C. endorse: This means to publicly support or approve. It is usually used without "to someone" ("endorse a product"), and it is less natural than "recommend" here.
• D. recommend: "Recommend something to someone" is a perfect collocation. Since the book is expensive, the teacher cannot suggest it to students. The meaning and grammar both fit.

Solution: "The textbook is very costly; I cannot recommend it to my students."

Tip: When a blank is followed by "to + person," test the verb's pattern. Recommend something to someone is a standard pattern, while afford never takes "to someone." Watch out for words that fit the meaning of the first clause (like "afford" with "costly") but break the grammar.