I am not sure that all … well with John.

Analyze the question You are asked to complete the sentence: "I am not sure that all _ well with John." This tests subject-verb agreement and idiomatic usage.

Explain the concept The expression "all is well" is a fixed idiom meaning "everything is fine." Here, "all" means "everything" and takes a singular verb. This is different from "all" meaning "everyone" (e.g., "All are present"), which takes a plural verb.

Solution, step by step

1. Identify the idiom: "all is well with (someone)" means things are going fine for that person.
2. Check the tense: "I am not sure that..." is present tense, so the clause that follows should be present tense too. This rules out A (Were).
3. Check the options: • A. Were: past tense, does not match "I am not sure." • B. Is: correct singular present verb, and it matches the idiom "all is well." • C. Are: would treat "all" as plural (people), which does not fit "well with John." • D. Will: needs a main verb after it, such as "will be," so "all will well" is ungrammatical.

Answer The correct option is B. Is.

Full sentence: "I am not sure that all is well with John."

Tip Remember the idioms "All is well" and "All's well that ends well." When "all" means "everything," use a singular verb. When it means "everyone," use a plural verb.