What is the main idea of the passage?

Jet lag happens because the body's inner clock lags behind a fast time-zone change (The passage explains jet lag as the gap between the body clock and a new time zone.)

According to the text, what mostly sets the body's inner clock?

Light (The text says the inner clock "is set mostly by light.")

Why does jet lag "barely happen" when you travel by ship or train?

The slow trip gives the body's clock time to adjust (The text says the slow way works "because the body has time to adjust.")

In this passage, "reset" most nearly means

set again to a new time (The clock "begins to reset to the new place," so reset means set again to a new time.)

Why Jet Lag Happens: Level 2 Reading Comprehension Questions

Fly across many time zones, and your body arrives before your inner clock does. This tired, foggy feeling is called jet lag. Inside every person is a kind of clock that tells the body when to sleep and when to wake. It is set mostly by light.

For a long time this clock matched the sky where you lived. Then a fast plane drops you in a place where noon feels like midnight to your body. Your inner clock still runs on the old time and takes several days to catch up. That is why, in a new time zone, you may feel wide awake at three in the morning and sleepy at noon.

Light is the best tool to fix it. Spend time outdoors in daylight, and your clock begins to reset to the new place. Going the slow way, by ship or by train, jet lag barely happens at all, because the body has time to adjust.

Comprehension questions