What this lesson covers
blank has to be placed against it.
This one builds the timeline on screen: the anchor lights up inside the sentence, every event
the sentence actually names drops onto one time axis, and the blank lands where those posts
force it. Then it walks the three wrong tenses and shows what moment each one is aimed at.
Also covered: the two limits on past perfect. It needs two past events, so one past event on
its own takes plain past; and when the verbs around the blank are present, the answer stays
present.
00:00 Four tenses, one timeline
00:17 The setup
00:49 The method: find the anchor
01:31 Two limits on past perfect
02:00 Your turn
02:34 Three ways this goes wrong
03:05 Recap
Chapters
- 0:00Four tenses, one timeline
- 0:17The setup
- 0:49The method: find the anchor
- 1:31Two limits on past perfect
- 2:00Your turn
- 2:34Three ways this goes wrong
- 3:05Recap
Lesson transcript
The narration of the video, word for word, under its chapter headings.
0:17The setup
One sentence, one gap, four tenses. The passage already tells you which one to use. Your job is to find the anchor, not to pick the tense that sounds right.
0:49The method: find the anchor
The anchor here is a date. By the time the survey crew reached the northern ridge in 1911. Reaching the ridge is the past event. The markers falling happened before that, so it needs a tense that sits further back. That tense is past perfect. Had fallen. Look at why the others fail. Has fallen and have fallen are present perfect, which ties the past to right now, and 1911 is not right now. Will have fallen points forward, into a future this sentence never mentions. Only had fallen puts one past event behind another past event.
1:31Two limits on past perfect
Not every pair of past events needs past perfect. If there is only one past event, plain past is correct. And when the verbs around the blank are present, stay present. The essay opens, and then it offers. Match the neighbours.
2:00Your turn
Your turn. Find the anchor, then pick the tense. Since the observatory opened in 1994, and the researchers are still using those instruments today. Past, running up to now, still going. That is present perfect. The answer is C. Have used.
2:34Three ways this goes wrong
Three ways this goes wrong. Choosing by feel instead of reading the verbs around the blank. Reaching for past perfect when there is only one past event. And skipping the time markers. Since. By the time. Already. And any year printed on the page.
3:05Recap
Find the anchor. Place the blank against it.
Read the written version: the Form, Structure, and Sense strategy guide, then try 25 hard Form, Structure, and Sense questions with full explanations. Both are free, no account needed.