#6 · Find the subject first.
The question. Which choice completes the text so that it conforms to the conventions of Standard English?
Hidden among the thousands of fossils ______ a single complete skeleton.
- is
- are
- were
- have been
The shortcut. Match the verb to the noun in front of the blank. It's the move your ear makes on its own, and when the subject sits right before the verb it's all you need. Here the noun in front of the blank is "fossils," so the ear says "are." (C and D are plural forms too, so they don't agree with the singular subject. The real choice is A or B.)
The fix: flip it
Put the subject first and read it straight into the verb: "A single complete skeleton ______ hidden among the thousands of fossils." Now your ear is right: a single complete skeleton is. (Khan Academy's advice, word for word: "try flipping the sentence.")
The same move with "there."
There ______ a dozen reasons to visit.
"There" isn't the subject; it's a placeholder that pushes the real subject after the verb. Ask what's there: a dozen reasons. Plural, so are, whatever the "a" in "a dozen" suggests.
When to reach for it. Flip when a sentence opens with a describing phrase ("Among…", "Beneath…"), starts with "there," or leads with a comparison ("less obvious is…"). If the choices differ only in number, find the subject before you trust the noun next to the blank.
The takeaway: find the subject first. When the verb comes before it, flip the sentence so the subject leads, then choose the verb.