I can't lend him my books. I … know him.

Analyze the question: The sentence says "I can't lend him my books. I __ know him." The blank needs an adverb that explains why I can't lend him the books, so it must mean I hardly know him.

Concept: Adverbs of frequency and degree:

• often means frequently. It makes no sense here, because knowing him well would be a reason to lend books.
• seldom and rarely mean "not often". They describe how frequently something happens, such as "I seldom see him".
• scarcely means "hardly, barely, almost not at all". It describes the degree of an action or state.

Solution:

1. "Know" is a stative verb, a state rather than an event that repeats. You don't "know" someone on occasion.
2. The idea we need is "I barely know him", which is a degree: I know him only very slightly.
3. "Often" gives the wrong meaning, so A is out.
4. "Seldom" and "rarely" are frequency words. "I seldom know him" and "I rarely know him" sound unnatural, so B and C are out.
5. "Scarcely" fits: "I scarcely know him" means "I hardly know him", which explains why I won't lend him my books.

Answer: D. scarcely

Exam tip: Use seldom/rarely with actions that repeat (I seldom visit, she rarely eats meat). Use scarcely/hardly/barely with states and abilities (I scarcely know him, I can hardly hear you). Also remember that scarcely, hardly, and barely already carry a negative meaning, so never add "not" to them.